Haditha (Iraq):  Suspected al-Qaeda gunmen, some wearing army uniforms, raged through a western Iraq city on Monday in a pre-dawn shooting spree that killed 26 policemen, including two officers shot execution-style.

The assault, launched at about 2:00 am (local time), saw insurgents dressed in military uniforms simultaneously attacking two checkpoints in the east and west of Haditha before storming other security posts and raiding the homes of the two officers.

Monday’s violence, the deadliest in Iraq since February 23, comes just weeks before an Arab League summit due to be held in Baghdad at the end of the month.

"A total of 26 policemen were killed, including a colonel and a captain, and three others were wounded when several armed men wearing security uniforms and carrying forged arrest warrants attacked several checkpoints," said Haditha police spokesman Major Tareq Sayeh Hardan.

"Al-Qaeda is responsible for this," Hardan said, noting that investigators found al-Qaeda literature in a vehicle that the attackers left behind.

Officers offered conflicting accounts of whether the attackers were riding in stolen army vehicles, or 4x4s with fabricated insignia.

According to police Lieutenant Colonel Owaid Khalaf, who said he was involved in some of today's firefights, the gunmen first attacked checkpoints at the eastern and western edges of Haditha.

"They then entered the town and were distributed throughout Haditha, where other gunmen were waiting for them in civilian cars," said Khalaf.

"More than 50 gunmen altogether started attacking checkpoints all over the town," he added, noting that at least one attacker was killed in the gunfights.