Britain was evacuating all its diplomatic staff from Iran on Wednesday, a day after protesters stormed its embassy in Tehran in scenes that prompted international outrage.
Norway said it had temporarily closed its embassy but its diplomats continued to work from elsewhere in Tehran. Other European missions were evaluating the situation.
Britain warned "serious consequences" would follow Tuesday's attacks on its two diplomatic compounds in the Iranian capital, one of which contained its embassy.
The protesters rampaged for hours through the properties, tearing down the British flag, smashing windows, trashing offices, setting documents alight, and briefly blocking the movements of six British diplomats.
The protesters had been taking part in demonstrations in front of the British compounds with the approval of authorities, to reflect official anger at Britain's announcement last week that it was cutting all relations with Iran's financial sector.
Britain's step was part of new sanctions coordinated with the US and Canada to pile pressure on Iran to halt its nuclear activities, which Western governments suspect is cover for a drive for a weapons capability.
The Tuesday attacks on the British compounds sharply increased tensions in the showdown between Iran and the West on the issue.
They were the worst assaults against a diplomatic mission in Tehran since the 1979 taking of the US embassy by Islamist students, who held 52 Americans hostage for 444 days — an act that resulted in the rupture of US-Iran diplomatic ties.
No British diplomats were hurt in Tuesday's incursions. But staff had to pull back to secure areas as the protesters went on their rampage.
A Foreign Office spokesman said the decision to withdraw "some" British staff from Iran was "to ensure their ongoing safety."
The spokesman did not specify how many were leaving nor whether the British embassy would be closed. "We'll make any announcement about our embassy and staffing levels at the appropriate time," he said.
European diplomats in Tehran told AFP, however, that all British diplomats were being evacuated. One said a first group had been taken to Tehran's airport for a flight to Dubai.
British, French, German schools — all located in one of the British compounds attacked — were closed until further notice, as a precaution, diplomats said.
International condemnation of the embassy assault was swift and broad.
The UN Security Council issued a statement slamming Iran, although it avoided mention of any repercussions.
UN chief Ban Ki-moon said in a separate statement he was "shocked and outraged to hear of the incident in Tehran in which demonstrators entered the British embassy, briefly abducted embassy staff and damaged property."
US President Barack Obama said the storming of the embassy was "not acceptable" and that "all of us are deeply disturbed."
Even Russia — Iran's closest major ally — condemned the incursions as "unacceptable."
Iran's reaction was a mix of contrition and defiance.
The foreign ministry expressed "regret" over the incident, and deputy police chief Ahmad Reza Radan was quoted by the state news agency IRNA as saying a number of protesters had been arrested and others were being sought.
But parliament speaker Ali Larijani said the protesters had been "angered by the British government's behavior" and the "decades of domineering moves by the British in Iran."
The UN Security Council's condemnation was "hasty," he told lawmakers, according to state television.
The head of parliament's security and foreign policy committee, Alaeddin Boroujerdi, said Iran "respects" all treaties protecting foreign diplomats and embassies.
"This issue must in no way cause concern for other diplomats and embassies," he was quoted as saying by IRNA.
Iranian newspapers generally abstained from commenting on the storming of the embassy, although all reported it on their front pages.
The Hamshahri newspaper, run by Tehran municipality, said the students were protesting "Britain's hostile stance," while the Mellat-e Ma daily headlined: "British embassy taken over in five minutes."
Britain has warned its nationals against non-essential travel to Iran, and advised the few in the country to stay indoors.
The storming of the two compounds came ahead of an EU foreign ministers' meeting on Thursday that is expected to unveil new sanctions against Tehran over its nuclear program.
Iran has repeatedly denied the program has a military component, and has warned it will respond to any attack by raining missiles on Israel and Turkey.