'There were no major violations in the election,' Guardian Council spokesman Abbasali Kadkhodai told the IRNA news agency.
The Council is expected to give its final ruling on Monday after supreme leader Ayatollah Ali Khamenei gave it an additional five days to investigate complaints filed by the defeated candidates.
Two weeks after the vote, protests in Tehran over Mahmoud Ahmadinejad's re-election have receded after the authorities responded with a fierce crackdown.
State-run English-language Press TV said yesterday that 20 people have been killed in the protests, including eight members of Iran's Basij militia.
Other state media have reported that 17 civilians have been killed.
In Italy, G8 foreign ministers said they 'deplored' post-election violence in Iran and urged the Islamic republic to 'respect fundamental human rights'.
