Cleric Ayatollah Ahmad Jannati yesterday claimed they had made confessions and would go to court.

In a prayer sermon referring to recent demos in capital Tehran, the head of Iran’s powerful Guardian Council, who is close to supreme leader Ayatollah Ali Khamenei, said: “In these events, their embassy had a presence.”

European Union countries backed Britain in demanding the release of the embassy staff. And Foreign Secretary David Miliband said: “We are urgently seeking clarification from the appropriate Iranian authorities.

“We are confident that our staff have not engaged in any improper or illegal behaviour.”

Eight embassy workers, all Iranian-born, were arrested at the weekend accused of inciting a rebellion against president Mahmoud Ahmadinejad.

Mr Miliband confirmed that two of them were still behind bars in Tehran and he said the Government was “deeply concerned” about them.

Two British diplomats have been expelled from Iran after the riots and protests that swept the country after its June 12 elections.

President Ahmadinejad claimed a landslide victory, but thousands of Iranians say the votes were rigged.

Britain has criticised Iran’s crackdown on the protesters.

And Ayatollah Jannati’s announcement follows public comments made by the supreme leader two weeks ago in which he branded the UK Iran’s “most treacherous” enemy.

Thousands of fanatics chanted “Death to Britain!” as Khamenai stirred them to frenzy.