Ten percent of Basra police are facing punishment over their conduct in recent fighting in the southern city, says Iraq's interior ministry.
About 1,600 officers have either been discharged, detained or are wanted for court martial for dereliction of duty, Maj Gen Abdulkarim Khalaf told the BBC.
He said they were being investigated for failure to open fire at outlaws, joining them or giving them weapons.
The government's operation in Basra tried to crush powerful militias there.
The operation, which involved Iraqi troops and was personally instigated by the Iraqi Prime Minister Nouri Maliki, began about two weeks ago and saw fierce fighting.
It ended with an Iranian-brokered deal that saw the militias off the streets but retain their weapons.
The police facing punishment have links with the main militia group, the Mehdi Army, which is loyal to the radical Shia cleric Moqtada Sadr, say local sources.
Maj Gen Khalif said the alleged renegades are being charged under Article 20 of the Security Law - violation of which, he said, carries a maximum penalty of death.