Iranian nuclear scientist Shahram Amiri has been thrust into the centre of the fraught psychological tensions that dominate relations between Tehran and Washington.

With Tehran keen to exploit every drop of propaganda from the scientist's alleged kidnap by CIA agents, more revelations are inevitable.

But so far, there are two contradictory narratives about the man, both told in his own words.

In a video message broadcast on Iranian state media on 8 June, a man claiming to be Mr Amiri said he was abducted by US and Saudi agents during a pilgrimage in Saudi Arabia in 2009.

"They took me to a house located somewhere that I didn't know. They gave me an anaesthetic injection," the man said in the video.

He said he was living in Tucson, Arizona, and said he had been subjected to eight months of "the most severe tortures and psychological pressures".

He described himself as an "expert and researcher" at Malek Ashtar University, but claimed that the US had wanted him to pretend he had stolen nuclear secrets.

This is the version Iranian officials have pushed, and Tehran claims to have passed on to the US evidence that he was abducted.

This is also the version Mr Amiri has now repeated in interviews with Iranian state media.

But another video message appeared on YouTube on the same day as the first, recorded apparently by the same man, entirely contradicting that version of events.

In the second video, he said he was in the US to continue his education, adding: "I am free here and I assure everyone that I am safe."

He said he was "not involved in weapons research and have no experience and knowledge in this field".

Malek Ashtar University has long been alleged to have a role in a nuclear weapons programme and on 9 June, the day after Mr Amiri's initial videos emerged, the university was put under UN sanctions.

'Mystery to many'

Other reports have muddied the waters still further, variously claiming that Mr Amiri had defected to the West and helped the CIA, or that he had actually been employed by Iran's Atomic Energy Organisation.

Reports from the US quote unnamed officials and security sources as saying Mr Amiri was a low-ranking technician who had defected and provided the US with useful corroborative evidence of Iran's nuclear programme.

According to these sources, Mr Amiri was put into a witness-protection programme, but became concerned for his family in Iran and, after suffering a breakdown, decided to return to his home country.

Mr Amiri showed up at the Iranian section of the Pakistan embassy in Washington on 13 June and demanded to be returned to Iran.

The Pakistani foreign ministry confirmed to the BBC that he had taken refuge at their embassy - the first time non-Iranian officials had confirmed any details about Mr Amiri.

Later, the US also acknowledged his presence - Secretary of State Hillary Clinton saying he was in the country "of his own free will" and was free to leave.

After months of flat denials from the state department that they had any information about Mr Amiri, department spokesman Philip Crowley revealed that he had been in the country "for some time", and the government had "maintained contact with him".

On 14 July, Iranian officials said he had finally left the US and was on his way back to Iran.

Mr Amiri has promised to clarify all of the allegations made about him when he returns.

"When I am hopefully in my dear country Iran, I can speak to the media and my own people with ease of mind, and tell them about my ordeal over the past 14 months, incidents that have been a mystery to many," state media quoted him as saying.