It was a memorial for the “martyrs” killed when the U.S. struck military bases in Syria, according to Iranian state television.

A small crowd sat in rows of folding chairs, men in the front and women in the back, at the main cemetery in Tehran, the Iranian capital, earlier this month. Children milled around and a young man passed a box of sweets. A man recited prayers through a microphone.

But the 12 fallen men weren’t Iranians. They were Afghans, according to other soldiers and local media reports, part of the Fatemiyoun Brigade, a largely overlooked force that dates to the height of the Syrian civil war a decade ago. To help President Bashar al-Assad of Syria beat back rebel forces and Islamic State terrorists, Iran at the time began recruiting thousands of Afghan refugees to fight, offering $500 a month, schooling for their children, and Iranian residency.

The brigade is still believed to be about 20,000 strong, drawn from Afghan refugees living mostly in Iran, and it serves under the command of the Quds Force, the overseas arm of Iran’s Revolutionary Guards.

Iranian media affiliated with the Guards and social media platforms dedicated to the Fatemiyoun published the names and photographs of the slain Afghans and said they were killed in U.S. strikes in Iraq and Syria. The U.S. strikes were conducted in retaliation for a January drone attack on a military base in Jordan that killed three American soldiers. The U.S. had blamed an Iran-backed militia based in Iraq for the attack.

Publicly, Iranian officials denied that any military personnel linked to Iran were among the casualties. Iran’s ambassador to the United Nations, Amir Saeid Iravani, told the U.N. Security Council days after the U.S. strikes that Iran had no connection to the bases attacked in Iraq and Syria. He accused the U.S. of falsely blaming Iran and said only civilians had been killed.

The Guards did not issue a statement acknowledging the deaths of the Afghans under their command as they typically do when Iranian forces are killed, nor did any official threaten to avenge the deaths.

The story of the Afghan casualties, however, emerged from at least four cities across Iran — Tehran, Shiraz, Qum and Mashhad — where the bodies of the Afghans were quietly repatriated to their families, according to photos and videos on Iranian media.

At the funeral processions, the coffins of the Afghans were draped in green cloth but bore the flag of no nation. In the cities of Mashhad, Qum and Shiraz, they were carried to religious shrines for blessings.

Some mourners carried the yellow flag of the Fatemiyoun Brigade with its emblem. Local officials, clerics and a representative from the Revolutionary Guards and members of the Afghan refugee community attended some of the funerals, according to photos and videos. Two little girls wearing matching pink jackets, their hair in ponytails, wailed at their father’s coffin at another funeral on the outskirts of Tehran.

“There is growing anxiety among Afghans that they are getting killed and Iran is not protecting them and disowning their martyrs to protect its own interests,” said Hossein Ehsani, an expert on militants and terrorism movements in the Middle East who is Afghan and grew up as a refugee in Iran. “They feel they are used as cannon fodder.”

Iran’s mission to the U.N. did not respond to a question about whether Mr. Iravani, the U.N. ambassador, was aware of the Fatemiyoun casualties when he spoke to the Security Council.

Afghans, including fighters for the Quds Force, expressed anger and frustration at Iran’s handling of these deaths, posting near-daily messages on a social media channel dedicated to Fatemiyoun voices. Some members questioned the silence of the Quds Force, calling it discrimination.

Among the men killed were two senior commanders who were close allies of the slain former Quds Force commander, Maj. Gen. Qassim Suleimani, according to Iranian media reports and photographs of them together in the Syrian battlefield. They were identified as Seyed Ali Hosseini and Seyed Hamzeh Alavi.

Mr. Suleimani was assassinated by the U.S. in 2020 in Iraq.

Most of the Afghans who fled to Iran over the years were Hazaras, one of the largest ethnic groups in their country who share the Shiite Muslim faith with most Iranians.

At home in Afghanistan, the Hazaras were among the natural allies of American forces because they shared common enemies in the Taliban and in Al Qaeda. But in the convoluted landscape of the Middle East today, they are now aligned with Iran and seeking to chase American forces out of the region.

In Syria, the Fatemiyoun force was often the first line of defense in the battle against ISIS and was widely credited for helping take back several Syrian cities. The government newspaper Iran said last week that at least 3,000 members of the force were killed in Syria over the years. The United States designated the Fatemiyoun as a terrorist organization in 2019.

A former member of the Fatemiyoun Brigade, an Afghan who was born and raised in Iran and was deployed to Syria three times, said he was drawn to the force because it provided an opportunity to escape crushing poverty and unemployment in Iran and gain legal status.

Asking that his that his name not be published for fear of retribution, he said many fighters also joined out of a desire to protect Shiite Islam and defeat a Sunni extremist force similar to the ones that had persecuted Hazaras in Afghanistan.

Another Afghan refugee, Mohamad, a 31-year-old Hazara Shiite and a former military officer in Afghanistan who fled to Iran when the Taliban retook the country, said in a telephone interview that he had a master’s degree but works in construction. Afghans also must worry about a growing crackdowns on undocumented migrants and threats of deportation, he said.

“One of my Afghan friends who is from my hometown told me he wants to join the Fatemiyoun out of pure financial desperation and fear of being sent back to Afghanistan,” said Mohamad, who asked that his last name not be used for fear of retaliation. “We are stuck, with no way forward and no way back.”

Analysts say that there is no evidence that Fatemiyoun forces were directly involved in attacks against American bases in Iraq and Syria, which the Pentagon says have been targeted more than 160 times by Iran-backed proxies since the start of the Israel-Hamas war in October. But the Fatemiyoun Brigade plays a significant role in helping Iran coordinate logistics on the ground for the network of militias it supports, funds and arms across the region.

The Fatemiyoun forces oversee bases that serve as key stops along the supply chain of weapons, including drones, missile parts and technology, that makes its way from Iran to Iraq and then Syria and to Hezbollah in Lebanon, according to analysts and a military strategist affiliated with the Guards, who asked not to be identified because he was not authorized to speak publicly.

“When the wider Syrian conflict froze several years ago, there was an expectation that Fatemiyoun would go home, disband and demobilize,” said Charles Lister the director of the Syria and Countering Terrorism and Extremism programs at the Middle East Institute in Washington. “But they have kind of melted into the wider regional network and have found a role to play — holding ground, coordinating logistics and wider coordination on the ground.”

American fighter jets destroyed the base where the Fatemiyoun were killed in Deir al-Zour, in eastern Syria, leaving a pile of rubble, mangled bricks and debris, according to a photograph published on the website Saberin News, affiliated with Iran’s proxy militias.

Maj. Gen. Patrick Ryder, a Pentagon spokesman, declined to comment specifically about the U.S. strikes killing Afghan fighters for Iran. But he said the strikes were conducted to hold the Guard and their proxies accountable and that “initial indications are that over 40 militants associated with Iranian proxy groups were killed or injured.”

Iranian commanders and key personnel were evacuated from the bases in anticipation of the American strikes as the Biden administration signaled for nearly a week that attacks were pending. But Afghans remained at the base, one Iranian official affiliated with the Guards said, adding that military bases couldn’t be abandoned.

At the funeral for five of the Afghans, including the two senior commanders, Hojatolislam Alireza Panahian, a prominent conservative cleric, told the mourners that the enemy was “dumb” to kill vulnerable Afghans.

“They are martyrs without borders, and jihadists for Islam and the resistance front.”

Eric Schmitt contributed reporting from Washington.

DOHA, Qatar — Taliban officials sent a defiant message to Western nations, donors and Afghan women’s groups this week, refusing to attend a conference hosted by the United Nations to discuss humanitarian crises facing Afghanistan and cooperation on human rights issues.

The two-day conference, which began on Sunday, was the second of its kind. It was held to try to chart a course forward for international engagement with the country. But the Taliban administration took issue with the inclusion of some groups at the meeting. Attended by special envoys from 25 countries and regional organizations, the conference is aimed at increasing international engagement with Afghanistan and developing a more coordinated response to the problems afflicting the war-torn nation.

The Taliban administration, the de facto rulers of Afghanistan since 2021, had been invited to the conference but at the last minute the group said it would not attend. In a statement, the Taliban’s Ministry of Foreign Affairs said it should be the sole official representative of Afghanistan for talks with the international community and only then could engage in frank discussions. Inclusion of others would hinder progress, the statement added.

“This government of Afghanistan cannot be coerced by anyone,” it stated.

Representatives from Afghan civil society, women’s groups, the Organization of Islamic Cooperation, the European Union and the Shanghai Cooperation Organization were present at the conference. Afghan political opposition parties, including the National Resistance Front, which has a small armed wing, were not invited, although they had asked to be included.

The Taliban administration’s decision, announced on the eve of the conference, appeared to have been made to avoid awkward conversations with Afghans living outside the country who oppose the Taliban authorities’ exclusion of women, and political opponents inside Afghanistan, several delegates said.

“The Taliban’s refusal to participate in the Doha Conference and engage in a meaningful dialogue with all sides, especially the brave women of Afghanistan, shows the group’s lack of interest in seeking a durable political settlement,” Fawzia Koofi, a former member of the Afghan parliament, said in a statement on X, formerly Twitter.

“I was hopeful until last night,” said Mahbouba Seraj, a women’s rights advocate. “We are divided into two halves. it is impossible to have half of Afghanistan here and half over in Afghanistan.”

She criticized the Taliban for complaining that it was “unreasonable” to have Afghans who were not members of the Taliban included in the conference.

Human rights groups and political opponents of the Taliban administration, which has declared the country an Islamic Emirate, say the Afghan government should allow a pluralistic political system and include women and ethnic minorities in its government.