Gholamali Khoshroo said an "unprecedented" number of international inspections in Iran had shown that the country only had peaceful objectives in its nuclear programme.

"The more they have searched, the more they have found that Iran has done nothing forbidden," Khoshroo said.

"Sometimes I am saying that maybe America is the only country that is unhappy that these results have come out and that Iran is not looking for weapons.

"Iran is not looking for weapons of mass destruction, why is America not happy?"

Britain, France and Germany are trying to offer economic and political rewards to convince Iran to dismantle an enrichment programme that the United States says is part of a covert plan to develop atomic weapons.