If heeded, the announcement could strengthen the image of the officers and soldiers trying to battle armed fighters and restore order in the country.
Still, it was not a full-fledged endorsement. The edict, endorsed by a group of 64 Sunni clerics and scholars, instructed enlistees to refrain from helping foreign troops against their own countrymen.
Ahmad Abd al-Ghafur al-Samarrai, a cleric in the Association of Muslim Scholars (AMS), read the edict during a sermon at a major Sunni mosque in Baghdad.
Criticising members of the current security forces, he said joining their ranks was now necessary to prevent the country's police and army from falling into "the hands of those who have caused chaos, destruction and violated the sanctities".
Al-Sadr calls for march
Meanwhile, Shia cleric Muqtada al-Sadr, who has led uprisings against US-led forces in the past, called on his supporters to stage a protest in the capital on 9 April, the second anniversary of Baghdad's fall, said Shaikh Hasan al-Idhari, an official at al-Sadr's Baghdad office.
Al-Idhari said the protesters will demand that the new Iraqi government set a timetable for the withdrawal of foreign troops and for the trial of former leader Saddam Hussein.