Mohsen Mirdamadi, secretary general of the Iranian Islamic Participation Front, warned that "new sanctions and even more dangerous actions" could result from the president's "self-praise and his sudden and overnight decisions."

The United States on Thursday imposed new unilateral sanctions against three Iranian banks, on the Islamic Revolutionary Guard Corps (IRGC) which it accused of spreading weapons of mass destruction, and on the elite Quds Force, which it designated a supporter of terrorism.

Washington acted after Iran refused to suspend its uranium enrichment programme which Tehran says is for peaceful electricity generation to which it, like other countries, has every right.

The US, backed by other Western powers and America's ally Israel, says it suspects Iran wants a nuclear bomb. Israel, which Ahmadinejad has said should be wiped off the map, is widely believed to be the only Middle East country with a nuclear arsenal.

Mirdamadi also criticised "unwise speeches and behaviour which reflect a violent, alarming and adventurous image from Iran" on the international scene.

The former MP also said that Iran's leaders did not have the right "to sacrifice the interests of the country with issues which are not a priority in foreign policy.

"The United States seeks confrontation at all costs. The situation is serious," Mirdamadi said on the sidelines of the event.

On the 10th anniversary of the party's congress, several senior members joined Mirdamadi in warning of the consequences of Tehran's atomic agenda.

"We must agree to temporarily suspend uranium enrichment for a short period, during negotiations, to avoid aggravating the situation," one party member told AFP on condition of anonymity.

Iran is in talks with the International Atomic Energy Agency as well as with EU foreign policy chief Javier Solana in a bid to find a breakthrough in the nuclear standoff.

The reformist party's congress came ahead of a new round of parliamentary elections due to take place in March 2008. The reformists lost the majority of seats to the conservatives in 2004.

Mirdamadi also criticised "the pressures against political activists and censorship" as well as the arrests of opponents.

He also touched on Ahmadinejad's economic policies, in particular the inflation rate which stood close to 16 percent.

Mirdamadi also slammed a drop in the economic growth by approximately 5.3 percent compared to previous years and spoke of an increase in the number of unemployed to three million, despite the unprecedented rise in Iran's oil revenues.

These figures resulted "in spite of injecting and spending 120 billion dollars of oil income in the economy of the country (in two years)," Mirdamadi complained.

related report
Iran reformist MPs protest Larijani exit
More than 20 Iranian reformist MPs on Sunday protested to President Mahmoud Ahmadinejad over the replacement of Ali Larijani as top nuclear negotiator, saying he should have acted with more thought.

"In circumstances when the nation is facing most sensitive times, a change of the top nuclear negotiator is not in line with the national interests and the good of the system," said a letter signed by 23 MPs.

"It was necessary for the president to act with more tolerance and thought," said the statement addressed to Ahmadinejad, quoted by the Fars news agency.

Fars said that the letter had been signed by 22 MPs from parliament's reformist minority and also by one conservative.

Iran last week announced the resignation of the relative moderate Larijani as top nuclear negotiator and his replacement by Saeed Jalili, a close ally of the president.

One hundred and sixty-seven MPs from across the conservative-dominated parliament last week signed a letter hailing Larijani's "valuable efforts" on the nuclear issue even if they stopped short of outright criticism of his departure.

There have already been complaints from the media and officials this was the wrong time for such a high level change. Even the foreign policy advisor to supreme leader Ayatollah Ali Khamanei said Larijani should not have quit.

Larijani had fallen out with Ahmadinejad over how to handle the Iranian nuclear dossier and had offered his resignation on several previous occasions.

However Larijani still attended talks with EU foreign policy chief Javier Solana in Rome alongside his successor, raising questions amongst observers about who was really in charge.

But foreign ministry spokesman Mohammad Ali Hosseini insisted that there was complete unity between Iranian officials over the nuclear issue.

"This round of talks (in Rome) with Mr Larijani and Mr Jalili was good and constructive and it showed the unified stance taken by our nation's officials."