LONDON - Britain said on Wednesday it had ordered the immediate closure of Iran's embassy in London and had closed its own embassy in Tehran after it was stormed by protesters.

"The Iranian charge (d'affaires) in London is being informed now that we require the immediate closure of the Iranian embassy in London and that all Iranian diplomatic staff must leave the United Kingdom within the next 48 hours," British Foreign Secretary William Hague told parliament.

"We have now closed the British embassy in Tehran. We have decided to evacuate all our staff and as of the last few minutes, the last of our UK-based staff have now left Iran," he said.

Hague also announced that Iranian ambassadors had been summoned in countries across Europe to receive strong protests over the storming of the British embassy.

Britain, locked in a confrontation with Iran over its nuclear activities, has voiced outrage over the ransacking of its diplomatic premises in Tehran on Tuesday by hardline students and Basij militia in revenge for new British and Western sanctions.

"If any country makes it impossible for us to operate on their soil they cannot expect to have a functioning embassy here," Hague said.

"This does not amount to the severing of diplomatic relations in their entirety. It is action that reduces our relations with Iran to the lowest level consistent with the maintenance of diplomatic relations," he added.

Hague said it was "fanciful" to think the Iranian authorities could not have protected the British embassy, or that the assault could have taken place without "some degree of regime consent".

He said European Union foreign ministers would discuss the embassy attack at a meeting in Brussels later on Wednesday and on Thursday. The EU ministers would discuss "further action which needs to be taken in the light of Iran's continued pursuit of a nuclear weapons programme," he said.

Britain and other Western nations accuse Iran of seeking to develop nuclear weapons but Tehran insists its programme is purely for peaceful purposes.