Iran's parliament voted on Sunday to expel the British ambassador in retaliation for fresh Western sanctions over Tehran's nuclear programme and warned that other countries could also be punished.

The bill they adopted, which now has to go to the Guardians Council for approval, demands that Iran's ambassador to Britain also be withdrawn as diplomatic relations are reduced to the level of charges d'affaires.

Economic and trade relations with Britain, already meagre, would be pared "to the minimum" under the text, which requires the measures be implemented within two weeks.

The lawmakers also raised the possibility of punishing "other countries that behave in a manner similar to that of Britain."

"This is only the beginning," parliamentary speaker Ali Larijani warned.

The session, carried live on state radio, saw 179 deputies vote in favour of the text, four against, and 11 abstain.

Britain described the vote to expel ambassador Dominick Chilcott within two weeks as "regrettable," and warned London would respond "robustly" if the threat was followed through.

"If the Iranian government acts on this, we will respond robustly in consultation with our international partners," a Foreign Office spokesman said.

"This unwarranted move will do nothing to help the regime address their growing isolation or international concerns about their nuclear programme and human rights record," the spokesman added.

Britain, whose City of London is the world's biggest financial centre alongside New York, said on November 14 it was "ceasing all contact" between its financial system and that of Iran.

That measure, announced in coordination with similar sanctions by the United States and Canada, came a week after a report by the UN atomic energy watchdog strongly suggesting that Tehran was researching nuclear weapons.

Britain and Canada have embassies in Tehran. The United States does not, having closed it after Iran's 1979 Islamic revolution. Canada's mission is already headed only by a charge d'affaires.

Prior to Chilcott taking up his post, the British mission in Tehran was also run by the embassy's charge d'affaires, but Britain decided to re-establish an ambassadorship in an effort to encourage dialogue.

Larijani said on Sunday that "the British government should be aware that the Majlis (Iran's parliament) is monitoring its actions carefully."

The bill's author, Alaeddin Borujerdi, who heads parliament's national security and foreign policy commission, said: "Should Britain cease its hostile approach to Iran, then we can upgrade ties once more."

Several lawmakers had wanted to take the bill further, by cutting off all diplomatic relations with London.

"We must sever all ties with Britain," said one, Mahmoud Ahmadi Bighash. "We must place a lock on the British embassy and ignore them until they come begging like the Americans."

Another, Hossein Sobhaninia, said: "Lawmakers should give a crushing response to British threats."

And another, Zohreh Elahian, charged that Britain had an "agenda of sedition aimed at toppling the Islamic republic" following Iran's contested 2009 presidential election.

Iran has dismissed the UN report as "baseless," and insists that its nuclear programme is for entirely peaceful purposes.

A protest against the new sanctions was planned for Tuesday in front of the British embassy, the Fars news agency reported.

EU nations were expected to unveil more sanctions against Iran at a foreign ministers' meeting next Thursday. France has called for a freeze on Iranian central bank assets and an embargo on Iranian oil.

Iran is already subject to four sets of UN sanctions designed to pressure it to halt its uranium enrichment activities, as well as unilateral Western sanctions.

Russia and China have slammed the latest Western sanctions, calling them illegal and a barrier to resuming stalled negotiations with Iran over its nuclear programme.