Dozens of Al-Qaeda fighters, some wearing army uniforms, killed 26 policemen in a wave of attacks on checkpoints and officers' homes across Haditha in west Iraq on Monday, police said.

The assault, launched at 2:00 am (2300 GMT on Sunday), saw insurgents dressed in military uniforms and riding in stolen army vehicles simultaneously attacking two checkpoints in the east and west of Haditha before storming other security posts and raiding the homes of two officers.

"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.

According to police Lieutenant Colonel Owaid Khalaf, who said he was involved in some of Monday'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.

Khalaf said the attackers also targeted two senior police officers' homes -- Colonel Mohammed Shauffeur and Captain Khaled Mohammed Sayil. They killed three bodyguards at each of the officer's houses, and kidnapped both.

Shauffeur's body was found in a Haditha marketplace and Sayil was discovered in an alleyway, blindfolded with fatal gunshots to the head.

"Right now, police, army and forces from the rest of Anbar are searching the entire town, and a curfew has been imposed," Khalaf said, referring to the province where Haditha lies.

The attack in Haditha, 210 kilometres (130 miles) northeast of Baghdad, is the first major instance of violence in the town since a suicide bomber blew himself up inside a bank, killing nine people including three police, and wounding eight others in March 2011.

Haditha is in western Sunni Arab Anbar province. It was one of several towns along the Euphrates valley that became Al-Qaeda strongholds after the 2003 US-led invasion that ousted Saddam Hussein.

However, in 2006, local Sunni tribes sided with the US military and unrest dwindled in Anbar as rebel fighters were ejected from the region.

Violence across the country is down from its peaks in 2006 and 2007, but attacks remain common. A total of 150 Iraqis were killed in February, according to official figures.