Islamabad: A key suspect in the suicide bombing that killed 150 people at the homecoming rally for the late Benazir Bhutto last year has been freed, his lawyer said on Monday.

Qari Saifullah Akhtar was released from prison in Karachi on June 8 "on the expiry of his detention period", said his attorney Hashmat Habib.

No charges were brought against Akhtar over the attack.

Bhutto survived the October attack, which targeted her motorcade in Karachi as supporters welcomed her back from exile.

The ex-premier was assassinated in December in the garrison city of Rawal-pindi.

She had accused Akhtar of involvement in the Karachi bombing in a book she finished writing before her assassination.

Akhtar was arrested in February in Lahore soon after Reconciliation: Islam, Democracy and the West, was published.

Authorities have claimed all along that Akhtar has links to Al Qaida.

His lawyer, however, has continuously pleaded his innocence, arguing that he had renounced militancy.

While acknowledging that Akhtar used to be a commander of an Islamist guerrilla faction that fought the Soviet occupation of Afghanistan in the 1980s, Habib has insisted he had nothing to do with the Karachi attack.

A court ordered Akhtar's release in March, but authorities quickly detained him again.