BBC NEWS | World | Middle East | Sunnis urged to join Iraqi police
Sunnis form the bulk of the anti-US insurgency, which frequently attacks the police and army.
A Iraqi government spokesman said the call on Sunnis to participate in the security forces was a welcome change.
Until recently, many Sunni clerics had branded the security forces as US collaborators.
The army and police are largely dominated by Shias and Kurds.
Map of Iraq showing location of Khan Bani Saad
Ahmed Abdul Ghafour al-Samarrai of the Association of Muslim Scholars said Sunni membership was necessary to prevent the forces falling into "the hands of those who have caused chaos, destruction and violated the sanctities".
However, the group consisting of 64 clerics and scholars also told Sunnis not to help foreign troops against their own countrymen.
The change of heart appears to have been prompted by January's elections when millions of Iraqis defied the insurgents to cast their ballots, says the BBC's Caroline Hawley in Baghdad.
Sunnis mostly boycotted the vote but have since been rethinking their role in Iraq's political future.