A member of Iraq's Governing Council said on Monday that 12 hostages had been freed and he was hopeful all remaining hostages would be freed later in the day.
Mr Mohsen Abdel Hamid said the release followed a decree issued by the Association of Muslim Clerics condemning hostage taking.
The association had also been in talks to try to secure the rest of the captives' release.
"The day before yesterday, the Association of Muslim Clerics issued a fatwa to ban (hostage taking) and due to this more than 12 individuals have been released," he told reporters.
"Last night we were also talking as much as possible to people in that area and we hope today the rest will be released, God willing."
He gave no details on the nationalities of the hostages he said had already been freed.
An unknown number of hostages are being held in Iraq. Three Japanese are believed still to be in the hands of guerrillas who have threatened to kill them if Japanese forces are not withdrawn from Iraq.
An American security contractor and several other contractors whose nationalities are not known are also either in the hands of guerrillas or missing.