Tehran: A top UN nuclear inspector arrived in Iran on Thursday for talks on cooperation with the International Atomic Energy Agency over Tehran's disputed nuclear programme, Iran's Irna news agency reported.

The visit aims at receiving fresh clarification over reports suggesting Iran is attempting to develop nuclear weapons, a charge Iran vehemently denies.

A report by Irna said: "The two parties will assess the trend of cooperation between Iran's Atomic Energy Organisation and the IAEA."

Olli Heinonen, the IAEA's deputy director, would hold talks in Tehran on Thursday and Friday, the report said.

Western powers threatened Iran with a new round of UN sanctions after it failed to accept an offer made by six world powers aimed at ending the dispute.

Diplomats in Vienna played down speculation that Heinonen, was on a special mission to verify the current level of Iranian enrichment activity, noting Iran had given no apparent sign of openness to the powers' "freeze for freeze" proposal.