More than 200 members of Iran's parliament have called for two leading opposition politicians to be tried on sedition charges.
Mir Hossein Musavi and Mehdi Karroubi have been accused of inciting anti-government protests at the behest of the United States and other countries.
One person is reported to have been killed during clashes with the security forces in Tehran on Tuesday.
A group of about 50 hardline members of the Iranian parliament say the opposition figures should be executed.
MPs say the two leaders are puppets of the west.
United States Secretary of State Hillary Clinton has said the US very clearly supports the protesters.