The comments by Ali Akbar Salehi, reported by the official IRNA news agency, were a further sign of worsening relations between Iran and the International Atomic Energy Agency (IAEA) since Yukiya Amano became IAEA Director General in December.

The Japanese has taken a sharper approach on Iran than his predecessor Mohamed El-Baradei, saying in reports that the Islamic state could be trying to develop a nuclear weapon now.

Iran has accused Amano of issuing misleading and politicized reports, and says the program is purely for power generation.

On Monday, Amano said Iran had "not provided the necessary cooperation to permit the Agency to confirm that all nuclear material in Iran is in peaceful activities."

He also said in a speech to his governing board that Iran's refusal to admit some inspectors was hampering the IAEA's work, a charge Iran rejects.

Iran says two inspectors it barred in June had provided "false" information about its nuclear program, and that it has the right to bar certain individuals. Amano said he had full confidence in the inspectors' professionalism and impartiality.

"Mr Amano made these remarks either knowingly or unknowingly. If it was knowingly, he made a big mistake, which is very dangerous because it indicates that he has been under political pressure," Salehi said on Tuesday.

Salehi, who is due to attend the IAEA's annual assembly in Vienna next week, said Amano was not "acting within the agency regulations."

Apart from those barred in June, Tehran canceled access for a senior Middle East inspector in 2006. It has also objected to a number of other inspector designations in the past.

Amano's latest report on Iran showed it was pushing ahead with its nuclear work in defiance of tougher sanctions, and voiced growing frustration over what the IAEA sees as Iran's failure to address concerns about possible military dimensions to its activities.

The United Nations Security Council has imposed four rounds of sanctions on Iran since 2006 over its refusal to halt uranium enrichment, which can have both civilian and military uses.