A missing Iranian nuclear scientist dramatically turned up at the Iranian interests section of Pakistan's embassy in Washington, and was quoted as saying he was kidnapped by U.S. agents in a "disgraceful act".
But a U.S. official, who declined to be named, said Shahram Amiri, who vanished during a pilgrimage to Saudi Arabia more than a year ago, had been visiting the United States and had decided "to return to Iran of his own free will".
Tehran has repeatedly accused the CIA of abducting Amiri, who worked for Iran's Atomic Energy Organisation, but ABC news had reported he defected and was helping the agency. Washington denied he was spirited away for nuclear secrets.
"My kidnapping was a disgraceful act for America, I was under enormous psychological pressure and supervision of armed agents in the past 14 months," Amiri, who is in his thirties, was quoted as saying in a phone interview with Iran's state TV.
Iran is locked in a dispute with the United States and its allies over Tehran's nuclear development programme that the West says is designed to produce nuclear weapons and which Iranian officials say aims to generate power.
The Amiri case provoked speculation about whether he had valuable intelligence about the Iranian nuclear programme that the Americans wanted.
"Mr. Amiri has been in the United States of his own free will and has decided to return to Iran of his own free will," the U.S. official said, adding Amiri is awaiting documents from a third country through which he plans to travel to Iran.
Amiri's surfacing comes after a Cold War-style spy swap which took place in Vienna on Friday when 10 people charged in the United States with being Russian agents were exchanged for four held in Russia on charges of spying for the West.
"Amiri has been escorted by American forces to Iran's interests section in Washington," Iran's PressTV said.
Iran and the United States severed diplomatic ties after the 1979 Islamic revolution. Under the umbrella of the Pakistani embassy, the interests section, which is staffed by Iranians, provides consular services including information on travel visas.
Iran's semi-official Fars news agency said the handover by U.S. agents was a victory over "American intelligence services". "Because of Iran's media and intelligence activities, the American government had to back down and hand over Amiri to the embassy last night," Fars said.
Iran summoned the Swiss ambassador to Tehran earlier this month and handed over documents which it said showed Amiri was kidnapped by the United States. U.S. interests in Tehran are handled by the Swiss embassy.
Confusing video footage of Amiri was aired in the past weeks. In one video, a man identified as Amiri, said he was taken to the United States and tortured.
In another video on the Internet, a man also said to be the scientist, said he was studying in the United States.
In a third video, a man describing himself as Amiri, said he had fled from U.S. "agents" and was in hiding, urging human rights groups to help him to return to Iran.
"Since my comments were released on the Internet, the Americans wanted to deny my abduction story altogether by sending me home secretly," Amiri said. "Americans saw themselves as the loser of this game."
Before Amiri disappeared, he also worked at Iran's Malek Ashtar University, an institution closely connected to the country's elite Revolutionary Guards. Tehran initially refused to acknowledge Amiri's involvement in Iran's nuclear programme.
Three months after Amiri's disappearance, Iran disclosed the existence of its second uranium enrichment site, near the central holy Shi'ite city of Qom in Iran, further heightening tension over the Islamic state's atomic activities.
Iranian authorities have repeatedly accused the United States of kidnapping and illegally detaining Iranians, including a former deputy defence minister who disappeared in 2007.
Some Iranian media linked the fate of three U.S. citizens, arrested near the Iraqi border a year ago where they said they were hiking and held on suspicion of spying, to the cases of alleged Iranian detainees in the United States. Iranian authorities have ruled out any prisoner exchange.
"They should be released immediately and allowed to return to the United States," the U.S. official said of the three.