Ayatollah's aide accuses Iran opposition leader of being US agent

A top aide to Iran's supreme leader has described the country's main opposition leader as a US agent and has called for him to be tried for crimes against the nation.

While hardline figures had previously demanded that Mir Hossein Mousavi be prosecuted for describing Iran's 12 June elections as fraudulent and leading demonstrations, this is the first public declaration claiming that Mr Mousavi is a foreign agent.

After quashing the post-election street demonstrations, Iran's leadership has been trying to erase any lingering doubts about the legitimacy of President Mahmoud Ahmadinejad's re-election by portraying the unrest as sparked by foreign meddling. "It has to be asked whether the actions of [Mousavi and his supporters] are in response to instructions of American authorities," said Hossein Shariatmadari, in an editorial for the conservative daily Kayhan, published on Saturday.

Shariatmadari does not hold a government position but is the powerful director of the Kayhan newspaper group and a close adviser to Iran's supreme leader, Ayatollah Ali Khamenei. He added that Mousavi was trying to "escape punishment for murdering innocent people, holding riots, co-operating with foreigners and acting as America's fifth column inside the country".

He called for Mr Mousavi and former reformist president Mohammad Khatami to be tried in court for "horrible crimes and treason", adding that there were "undeniable documents" proving Mr Mousavi's foreign links.

On Friday, another powerful hardline cleric said that Iran would put a local employee of the British embassy on trial for being involved in the demonstrations, in a further effort to prove foreign elements were behind the unrest. The Guardian reported that the embassy's chief political analyst, a 44-year-old Iranian, had been charged at Tehran's Evin Prison with "acting against national security".

Eight embassy staff were arrested last weekend amid rapidly deteriorating relations with Iran since the disputed re-election of President Ahmadinejad. All but one have been released.