A newspaper editorial is raising the prospect that Iran's main opposition leader could be arrested and charged over the country's postelection chaos.

A top aide to Iran's supreme leader is accusing Mir Hossein Mousavi of being an American agent who should be tried for treason. In the conservative daily (Khayan), the aide called for Mousavi and former reformist President Mohammad Khatami to be tried in court for "horrible crimes and treason."

Mousavi maintains he won the June election, not incumbent President Mahmoud Ahmadinejad and issued a statement earlier this week saying he considers the government illegitimate.

An Iranian lawyer says about a dozen prominent reformist leaders have been detained since protests began after the elections. Police say more than a thousand people have been detained in total and 20 protesters killed during the violence. Eight members of the paramilitary militia have also been killed.