The Iranian government says it has evidence that one of its nuclear scientists was abducted and is being held in the US against his will.
Shahram Amiri disappeared a year ago while on a pilgrimage to Saudi Arabia.
A video broadcast by Iranian TV purports to show Mr Amiri saying he was kidnapped and is living in Arizona.
Hours later, another video posted on YouTube appeared to show the scientist saying he was happy in America. The US denied abducting him.
The contradictory accounts of Mr Amiri’s fate have emerged days before the UN Security Council is due to vote on a fourth round of sanctions against Iran over its nuclear programme. Mr Amiri worked as a researcher at a university in Tehran, Iranian media reported. But other reports said he worked for the country’s Atomic Energy Organisation and had in-depth knowledge of the country’s nuclear programme.
In the video shown on the Islamic Republic of Iran Broadcasting network, the man says he was forced to say he defected with a laptop full of evidence about Iran’s nuclear secrets and that he was being used to put pressure on Iran.