Iran summoned the Swiss ambassador in Tehran on Tuesday to hand over documents as evidence of an alleged kidnapping by the United States.

Shahram Amiri, a university researcher working for Iran's Atomic Energy Organisation, disappeared during a pilgrimage to Saudi Arabia a year ago. Tehran accused Riyadh of handing him over to the US, a charge Saudi Arabia has denied.

Swiss Ambassador Livia Leu Agosti was to be given proof that the nuclear scientist had been abducted, the official IRNA news agency reported.

Iran has no diplomatic relations with the US and American interests in Tehran are handled by the Swiss embassy.

Iran's state television showed on Monday a video of what it said was Amiri. In the footage Amiri said he had been kidnapped and taken to the United States where he was "tortured".

Iran's nuclear ambitions have been cause for concern among world leaders. Key United Nations Security Council powers agreed on Tuesday on a list of new Iranian individuals and firms to be blacklisted under a fourth round of UN sanctions. The draft resolution could be voted on as early as Wednesday.

In May, facing such sanctions, Iran agreed to ship most of its uranium out of the country to be enriched. The proposal, hashed out by the top leaders of Brazil, Turkey and Iran, is nearly identical to one forged in Switzerland last autumn that the Iranians later rejected. Some observers wondered whether the new deal was an attempt by Iran to buy time.

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