TEHRAN: A powerful Iranian cleric said today that British embassy local staff arrested for allegedly stoking post-election unrest will be put on trial, a move that prompted coordinated protests from European governments.

Britain's Foreign Secretary David Miliband said he was "urgently seeking clarification" about the announcement as governments across the 27-nation European Union called in Iranian ambassadors.

"In these incidents, their embassy had a presence, some people were arrested. Naturally they will be put on trial, they have made confessions," Ahmad Jannati, head of Iran's Guardians Council, said at Friday prayers.

A total of nine local staff were initially arrested late last month, but the British government said seven have now been released, while Iranian state television has said only one remains in custody.

Miliband said he was "deeply concerned" about British staff being detained.

"We have noted the remarks by Ayatollah Jannati suggesting that some of our local staff in Iran may face trial," he said in a statement.

"We are urgently seeking clarification from the appropriate Iranian authorities. I intend to speak to Foreign Minister (Manouchehr) Mottaki.

"We are confident that our staff have not engaged in any improper or illegal behaviour. We remain deeply concerned about the two members of our staff who remain in detention in Iran." Tehran accused the embassy employees of instigating riots in the unrest that erupted over the disputed re-election of President Mahmoud Ahmadinejad, which his rivals said was fraudulent and marred by widespread irregularities.

Jannati, who is close to Iran's supreme leader Ayatollah Ali Khamenei and a strong Ahmadinejad supporter, said the country's "enemies" had been plotting a "velvet revolution" in the Islamic republic.

He said London had predicted "street riots" around the June 12 election and had warned Britons to stay away from public places.

Khamenei has described Britain, which has long had turbulent relations with Iran and a lengthy history of mistrust, as the "most evil" of its enemies.

EU governments called in Iranian envoys in protest at the action against the British embassy staff, a source close to the Swedish EU presidency said.

"We are summoning the Iranian ambassadors throughout the European Union and we will be monitoring the situation next week concerning the local personnel from the British embassy," the source told AFP.