European Union foreign ministers agreed on Sunday the bloc would meet any Iranian intimidation of European diplomatic staff in Tehran with a "strong and collective response", Britain said.

British Foreign Secretary David Miliband said the ministers at a meeting on the Greek island of Corfu unanimously called for the immediate release of British embassy local staff detained by Iranian authorities.

"There was also a commitment that harassment and intimidation of (Tehran) diplomatic staff of European countries will be met with a strong and collective response, " he told reporters.

Earlier on Sunday, Miliband called the detentions "harassment and intimidation of a kind which is quite unacceptable".

"These are hardworking diplomatic staff. The idea that the British Embassy is somehow behind the demonstrations and protests that have been taking place in Tehran. ... is wholly without foundation."

Iranian media reported Sunday that authorities had detained eight local employees of the British Embassy in Tehran for an alleged role in postelection protests, signaling a hardening of Iran's stance toward the West.

Miliband said some of the employees had been released following their detention, but that others continued to be held. He said "about nine" workers had initially been detention. It was not clear how many of those had been released.

"At the moment our top priority is the position of our locally engaged staff, who we want to see released, unharmed and back at work," Miliband said.

Iran has accused Western powers - Britain and the United States in particular - of interfering in its internal affairs after the vote, which sparked days of huge demonstrations in which at least 20 people were killed.

Britain and the United States have rejected the accusations.

"Eight local employees at the British embassy who had a considerable role in recent unrest were taken into custody," the semi-official Fars News Agency said, without giving a source. "This group played an active role in provoking recent unrest."

Iran's English-language state Press TV carried a similar report, citing Iranian sources.

In London, a foreign ministry spokesman said, "We have in the last few days received a number of sometimes confused reports that British nationals or others with British connections have been detained. We continue to raise them with the Iranian authorities."

A senior diplomat from another Western country said the reported detentions were a "worrying development".

Official results showing hard-line President Mahmoud Ahmadinejad won re-election by a landslide were met with disbelief by many Iranians who agreed with complaints by the runner-up, Mirhossein Mousavi, that the vote was rigged.

The authorities accuse Mousavi of responsibility for the bloodshed that occurred when riot police and religious basij militia crushed the protests. Mousavi blames the government.

Iranian officials have over the last week stepped up accusations of foreign interference.

Foreign Minister Manouchehr Mottaki said Tehran was considering downgrading ties with Britain, and Intelligence Minister Gholamhossein Mosheni-Ejei said some people with British passports were involved in this month's unrest.

British Prime Minister Gordon Brown announced on June 23 that Britain was expelling two Iranian diplomats after Iran forced two British diplomats to leave.

Britain has a long history of involvement in Iran and many Iranians remain suspicious of its motives.

The two countries have frequently clashed over Iran's nuclear program, which the West suspects is aimed at developing nuclear weapons. Iran denies this, saying it only wants nuclear power for generating electricity.

Supreme Leader Ayatollah Ali Khamenei on June 19 attacked foreign powers for alleged interference, singling out Britain as the "most treacherous" of Iran's enemies.

Brown has condemned violence and media censorship in Iran.

Britain suspended its diplomatic ties with Iran after the Islamic revolution in 1979, only reopening an embassy in 1988, following the Iran-Iraq war. Ties were downgraded again in the early 1990s, with full normalization only taking place in 1998.

In 2007, 15 British sailors and marines were seized by Iran in the Gulf and released after a tense 13-day standoff.