Iranian state television said on Tuesday seven people had been killed near the site of a rally in Tehran.
Iran's English-language Press TV carried a breaking news headline citing radio as saying Seven people killed near illegal Tehran rally.
It did not specify if the dead were opposition supporters or others.
It also said several people were wounded when thugs tried to attack a military post.
Tens of thousands of supporters of defeated presidential candidate Mirhossein Mousavi defied a government ban on Monday to demonstrate in downtown Tehran against the official result of last Friday's presidential election, which showed hardline President Mahmoud Ahmadinejad won a landslide.
An Iranian photographer said Islamic militiamen killed one man during Monday's march when people in the crowd attacked a station of the Basij religious militia.
(Editing by Angus MacSwan)