An Iranian medical researcher who was prevented from entering the United States to work at a Boston hospital is believed to have been an active member of the Basij force used in Iran as a tool of state repression.

Seyed Mohsen Dehnavi was the head of the Basiji at Tehran's Sharif University, former students at the university and activists claim.

Several former Sharif University students who did not want to be identified because of fear of government harassment told RFE/RL that Dehnavi was involved in putting pressure on reformist students.

Media reported that Dehnavi, who was identified as a cancer researcher, was detained at Boston's Logan Airport on July 11 and later sent back to Iran, despite traveling on a valid visa to work as a scholar at Boston Children's Hospital, which is affiliated with the Harvard Medical School.

"Dr. Dehnavi is a visiting research scholar on a J-1 visa coming to Boston Children's with his wife and three children," the hospital said in a statement. The hospital did not respond to a request by RFE/RL for comment on Dehnavi's alleged connections to the Basij.

Visa Denial 'Unrelated' To Travel Ban

Later, U.S. Customs and Border Patrol spokeswoman Stephanie Malin was quoted by the AP news agency as saying that Dehnavi and his family were put on a return flight to Iran shortly after 9 p.m. on July 11.

She said the Dehnavi family's detention was for "reasons unrelated" to President Donald Trump's executive order that bans entry to the United States to most people from six predominantly Muslim countries, including Iran.

Malin added that Dehnavi's entry refusal was based on information uncovered during a review by the Customs and Border Patrol and that foreigners can be denied entry on several grounds, including criminality, security concerns, and health-related issues.

It is not clear why Dehnavi and his family were not allowed into the United States.

After he had criticized Dehnavi's detention on Twitter, National Iranian American Council (NIAC) President Trita Parsi said that it was unlikely he was denied entry because of his reported Basiji background.

Parsi later told RFE/RL's Radio Farda in an e-mail that "we were not aware of anything about his background except that he was a cancer researcher admitted to a postdoc at Harvard. I find it unlikely that his denial of entry had anything to do with his past in the Basij, since these are things that are carefully reviewed before he even gets a visa."

News of Dehnavi's detention and deportation received widespread coverage, but no reports included information about his alleged Basij background.

Former students in Iran told RFE/RL that Dehnavi benefited from privileges given by the state to Basij members for their service. Active Basiji are often given reserved positions at universities and other bonuses.

Iranian activists and others posted on social media sites about Dehnavi's alleged Basij background immediately after news of his detention was reported.

"He was among [the Basiji] who would photograph students protesting inside or outside the university," a former Sharif University student told RFE/RL on July 12.

"Then a few days later, those students would be arrested," he said.

'Physical' Attacks

The same student also claimed that Dehnavi had been involved in "physical" attacks on students in 2009.

Another former Sharif student currently based in North America said he recalls Dehnavi being omnipresent at Basij actions aimed at pressuring pro-reform students and suppressing dissent.

"He would speak loudly and harshly and attack the other side," he said. "But to be fair I must say I don't recall seeing him physically attacking students."

RFE/RL could not independently verify the allegations. Several attempts to contact Dehnavi for comment about his alleged work with the Basij were unsuccessful.

Mohammad Rashidian, a friend of Dehnavi who had posted about the detention on Facebook, also did not respond to an RFE/RL request for comment.

'Serious Human Rights Abuses'

Rights groups and witnesses have said that the Basij and the Islamic Revolutionary Guards Corps (IRGC) were active in the 2009 brutal crackdown on protesters across Iran in the aftermath of disputed presidential election.

The United States imposed sanctions on the IRGC and the Basij in 2011 "for being responsible for or complicit in serious human rights abuses in Iran since the June 2009 disputed presidential election."

"I don't understand why [Dehnavi] was given a U.S. visa despite his background in the Basij," the North American based former Sharif university student said.

He said he was glad Dehvani was denied entry into the United States.

"This is the price he paid for the bad things he did in Iran," the student added.

"People like him attack everyone for being a friend of the U.S. but he himself he tramples on all those [stated values]," a former Sharif University student living in Iran told RFE/RL.

But he added: "It would actually be a good for him to live and study abroad, it might soften his [hard-line] beliefs."

There was also heavy criticism of Dehnavi on social media.

"He gets paid by the student Basij to burn the U.S. flag then he expects to be allowed into the U.S," commented an Iranian on Twitter.

Iran's volunteer paramilitary Basij militia, formed following the 1979 Islamic Revolution, is notorious for its anti-U.S. stances.

Its members are involved in maintaining law and order, preserving Islamic morals and values, and also acting against internal dissent and critics.

Basiji are very active at schools, universities, and other state institutions.

Amir Etemadi, the chief editor of the opposition media outlet Taghato, which also posted about Dehnavi's alleged Basij background, says he's not surprised that a Basiji would want to live in the United States.

"I know that despite all the bad things they say about the United States -- they trample on the U.S. flag, they burn it -- one of their main wishes is to live in the U.S.," he said.

"In Iran, [the hard-liners] say one day we will turn the White House into a [mosque]," Etemadi said. "It's the slogan of IRGC and Basij members. It may be an exaggeration but I think they believe in this slogan. They believe they have to come to the United States if they want to deal a blow to the country."

Etemadi -- who is based in Washington, D.C. and was jailed in Iran for his activism -- said he began investigating Dehnavi's background because his name sounded familiar.

On Instagram, Etemadi said he managed to find a post by a friend of Dehnavi who lamented the detention at the Boston airport.

"Hostility, injustice, and cowardice...are among the worst characteristics of the demonic and unclean Satan, the United States," the post said.