Supreme Leader Ayatollah Ali Khamenei has ordered the closure of the Kahrizak detention centre where detainees are believed to have been held since Iran's disputed presidential election.

The order is regarded as a move to calm simmering discontent among leading moderates and their supporters, particularly when the clerical establishment faces rifts over President Mahmoud Ahmad-inejad's appointment of his first vice-president.

Lawmaker Kazem Jalali said 140 detainees were released from Evin prison after members of a parliamentary committee visited the prison yesterday, ISNA reported. "Those with minor charges have been released on bail," said Mr Jalali.

The semi-official Mehr news agency quoted Mr Jalali as saying the detention centre was ordered closed because it could not preserve the "rights of detainees".

Reformist websites have reported some detainees involved in protests following the June 12 election were being held at Kahrizak under "severe physical and mental pressure".

"Kahrizak is the detention centre which the leader ordered closed because it lacked necessary conditions to preserve rights of detainees," said Mr Jalali, spokesman of a special parliamentary committee set up to investigate detentions after the election.

Mr Jalali said 150 people who were involved in post-election protests and 50 others, including political activists, members of anti-revolution groups and some foreigners, remained in jail following the releases from Evin.

Rights groups say hundreds of people, including senior pro-reform politicians, journalists, activists and lawyers, have been detained since the election.