A missing Iranian nuclear scientist, who Tehran says was kidnapped by the CIA, has taken refuge in the Iranian interests section of Pakistan's embassy in Washington, a foreign ministry official told Iran's news agency.
"We contacted the Pakistani embassy and they confirmed that Shahram Amiri has taken refuge there," the IRNA state news agency quoted the unnamed official as saying today. "Further details will be revealed soon."
A Pakistani foreign ministry official in Islamabad also confirmed that the scientist was in the Iranian section of Pakistan's embassy, not in the embassy itself.
Iran's state radio said earlier today that Mr Amiri, a university researcher who disappeared during a pilgrimage to Saudi Arabia a year ago, was at the mission. "He wants to be returned to Iran immediately," state radio said in its report.
Iran and the United States severed diplomatic ties shortly after the country's 1979 Islamic revolution. The Pakistani embassy looks after Iran's interests in the United States.
Iran's semi-official Fars news agency said Amiri was handed over to the embassy by US agents, calling it a defeat for "America's intelligence services".
"Because of Iran's media and intelligence activities, the American government had to back down and hand over Amiri to the embassy on Monday night," Fars said.
Officials at the State Department and at the Pakistan embassy in Washington were not available for comment.
Iran accuses the United States and Saudi Arabia of abducting Mr Amiri, who worked for Iran's Atomic Energy Organisation. US and Saudi officials have denied the accusation.
Iran summoned the Swiss ambassador to Tehran earlier this month and handed over documents which it said showed Amiri had been kidnapped by the United States. US interests in Tehran are handled by the Swiss embassy.
Confusing video footage of Mr Amiri was aired in the past weeks. In one video, a man identified as Mr 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 Mr Amiri said he had fled from US "agents" and was in hiding, urging human rights groups to help him to return to Iran.
In March, ABC news said Mr Amiri had defected to the United States and was helping the CIA. Before he 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 Mr Amiri's involvement in Iran's nuclear programme, which the West fears is being used to develop nuclear weapons and which Iran says is designed to generate electricity.
Three months after Mr Amiri's disappearance, Iran disclosed the existence of its second uranium enrichment site, near the central holy Shia city of Qom, 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 have linked the fate of three US citizens, arrested near the Iraqi border a year ago where they said they were hiking and held on suspicion of spying, to the case of alleged Iranian detainees in the United States.
But Iranian authorities ruled out the possibility of any prisoner exchange.