Iran's supreme leader has ordered the pardon of 100 'security'-related prisoners including some involved in the huge protests against the disputed June 2009 re-election of President Mahmoud Ahmadinejad.

The decision, reported late on Saturday by the semi-official Mehr news agency, appeared timed to coincide with Ramadan which is in its final days, when compassionate release is sometimes issued to prisoners.

Seventy of the 100 were due to be released immediately, on Saturday night, Mehr said. The others either had their sentences reduced or suspended.

'Based on an agreement of the supreme leader (Ayatollah Ali Khamenei), 100 prisoners charged with security crimes have been granted amnesty. Some of them were involved in post-election sedition two years ago,' Mehr said. 

The report did not name the pardoned prisoners and there was no indication it included two Americans who were sentenced to eight years' jail last week for spying after they crossed the border from Iraq where they said they had been hiking.

The release comes as Iranian politicians start preparing for parliamentary elections due next March which will be the first national poll since the presidential race which brought unprecedented numbers of protesters onto the streets.

Most reformists have yet to say whether they will run for election. Iranian authorities are likely to ban people from standing who were connected to the post-election unrest.

Opposition leaders Mehdi Karoubi and Mirhossein Mousavi have been held under house arrest since February when they called the first Green Movement demonstration for more than a year.

The group International Campaign for Human Rights in Iran estimated at least 100 people were killed in the unrest which the government blamed on 'seditionists' funded by Iran's foreign enemies. Many more were arrested. – Reuters