The official Iranian news agency IRNA on Saturday quoted a foreign ministry spokesman as saying that such a visit was "not on our agenda."

"No plans for US congressmen or senators to visit Iran have been made and this sort of trip is not on our agenda," spokesman Hamid Reza Asefi said.

His denial came a day after a US senator announced that a group of US congressional aides were to go to Iran in February on the first official US visit to the country since the 1979 Islamic revolution.

Senator Arlen Specter, a Pennysylvania Republican, said the visit could set the stage for a later mission by US lawmakers.

The senator, who had met the Iranian ambassador to the United Nations Muhammad Javad Zarif, said the US delegation was "confirmed" for February.

Bitter past

The US severed relations with Iran in 1980 following a crisis over hostages seized from the US embassy in Tehran.

Only two years ago, President George Bush said Iran was part of a weapons proliferating "axis of evil" along with Iraq and North Korea.

Despite continuing to be at loggerheads, strained relations between the US and Iran have shown signs of a slight thaw.

The US provided relief assistance to the Iranian city of Bam, devastated by an earthquake in December.