Shahram Amiri, an Iranian nuclear scientist who disappeared a year ago, holds his 7-year-old son Amir Hossein as he arrives today at Imam Khomeini airport just outside Tehran, Iran. Amiri claimed today he suffered mental and physical torture at the hands of U.S. interrogators after disappearing last year, adding to Tehran’s allegations he was abducted by American agents.

Tehran, Iran ? An Iranian nuclear scientist claimed today that he suffered extreme mental and physical torture at the hands of U.S. interrogators after disappearing last year, adding to Tehran’s allegations he was abducted by American agents.

The U.S. says he was a willing defector who changed his mind and decided to board a plane home from Washington.

However, The Washington Post said in its online edition late Wednesday that Shahram Amiri had been working for the CIA for more than a year. It said he was paid $5 million out of a secret program aimed at inducing scientists and others with information on Iran’s nuclear program to defect.

Amiri was embraced by his family — including his tearful 7-year-old son — after arriving in Tehran in the latest spectacle of a puzzling series of events that left Iran and Washington with starkly different accounts. Amiri flashed a V-for-victory sign as he stepped into the terminal.

Iran has portrayed the return of Amiri as a blow to American intelligence services that were desperate for inside information on Iran’s nuclear program. Iran has sought maximum propaganda value — allowing journalists to cover Amiri’s return and having a top envoy from Iran’s Foreign Ministry on hand to greet him.

Washington described the 32-year-old Amiri as someone who reached out to U.S. officials, but have offered few other details.

Speaking to journalists after a flight via Qatar, Amiri repeated his earlier claims that he was snatched while on a pilgrimage last year in the Saudi holy city of Medina and carried off to the United States.

He claimed he was under intense pressures during the first few months after his alleged kidnapping.

“I was under the harshest mental and physical torture,” he said at Tehran’s international airport, with his young son sitting on his lap.

He also alleged that Israeli agents were present during the interrogations and that CIA officers offered him $50 million to remain in America. He gave no further details to back up the claims or shed any new light on his time in the United States, but promised to reveal more later.

“I have some documents proving that I’ve not been free in the United States and have always been under the control of armed agents of U.S. intelligence services,” he told reporters.

He sought to downplay his role in Iran’s nuclear program — which Washington and allies fear could be used to create atomic weapons. Iran says it only seeks energy-producing reactors.

“I am a simple researcher who was working in the university,” he said. “I’m not involved in any confidential jobs. I had no classified information.”

His case was often raised by Iranian officials in the past year, but Washington offered no public response. It took a higher profile after Iranian authorities decided to pursue charges against three American hikers captured in July 2009 on the Iran-Iraq border.

Iran’s deputy foreign minister, Hassan Qashqavi, said there would be “no link” between Amiri’s return and the case of the three Americans, who claim they inadvertently strayed into Iran while hiking.

Amiri was generally a footnote in the international showdown over Iran’s nuclear ambitions until last month. Iranian state TV aired a video he purportedly made from an Internet cafe in Tucson, Ariz., to claim he was taken captive by U.S. and Saudi “terror and kidnap teams.”