A wave of attacks in Iraq, including car bombs in Baghdad, killed 73 people on Wednesday as militants took more territory from security forces in crisis-hit Anbar province.

The twin setbacks for authorities, grappling with Iraq's worst period of unrest since the country emerged from a sectarian war that killed tens of thousands, come just months before a parliamentary election.

UN chief Ban Ki-moon and other diplomats have urged Iraq's leaders to seek political reconciliation to resolve nationwide violence and the standoff in Anbar.

But Prime Minister Nuri al-Maliki has ruled out dialogue with militants as his forces have launched wide-ranging security operations.

However the operations, which authorities say have led to the death or capture of several militants affiliated with the Al-Qaeda-linked Islamic State of Iraq and the Levant (ISIL), have not stopped the bloodshed.

Nine car bombs hit civilian targets in majority-Shiite or confessionally mixed neighbourhoods of the capital, killing 37 people.

One of them struck a packed market in the Shaab neighbourhood, while another detonated outside a restaurant on Sanaa Street, killing five peoples, an AFP journalist reported.

The windows of nearby shops were shattered, the restaurant's ceiling partially caved in and blood and mangled vehicle parts scattered across the street.

The Baghdad carnage could have been much worse, with police saying they managed to arrest four would-be suicide bombers, all allegedly Arabs of foreign nationalities, with explosives-rigged vehicles that were eventually disabled by security forces and military engineers.

They did not provide more details about the thwarted attackers, who were nabbed in four different Shiite neighbourhoods of the capital.

A suicide bombing at a funeral in Buhruz, in religiously mixed Diyala province north of Baghdad, killed 16 people and wounded 20, officials said.

The funeral was for a member of the Sahwa, the Sunni tribal militia who sided with the US military against their co-religionists in Al-Qaeda from 2006, helping turn the tide against the jihadists.

They are often targeted by Sunni militants who regard them as traitors.

In and around the main northern city of Mosul, 13 people were killed, nine of them soldiers, while seven employees of a brick factory were shot dead in Muqdadiyah, 80 kilometres (50 miles) north of Baghdad.

Government loses ground in Anbar

Although no group has claimed responsibility for the bloodshed, Sunni militants affiliated to ISIL often carry out coordinated attacks on civilians and target Sahwa fighters.

Maliki appealed for international action against Al-Qaeda and its affiliates.

"It may take time," he said in his weekly televised address, "but... to keep silent means there would be sub-states creating problems for the security of the region and the world."

He called for "a strong position against countries who give support" to militants and urged world powers to "drain the resources of terrorists."

But the security forces lost more ground in Anbar province, west of Baghdad, as Sunni gunmen, including some linked to Al-Qaeda, overran two areas when police abandoned their posts.

The losses mark a second day of setbacks for government forces and their tribal allies as they try to retake territory on the capital's doorstep.

The militants and anti-government tribal allies hold all of the former insurgent bastion of Fallujah and parts of the provincial capital Ramadi, farther west.

The crisis marks the first time militants have exercised such open control in major cities since the height of the insurgency that followed the US-led invasion of 2003.

"We gave ourselves up, and we gave up our arms to Daash," one policeman from the town of Saqlawiyah, who did not want to be identified, told AFP using the commonly used Arabic name for ISIL.

"They have very heavy arms, which are much stronger than what we have. Our police station was not very well protected, and they surrounded us. Even when we called for support, nobody came."

Militants overran the police station in Saqlawiyah and retook one in Malaab, a major district of Ramadi, just days after security forces trumpeted their successes in the area.

And clashes erupted periodically in Ramadi and on the outskirts of Fallujah from Tuesday evening into Wednesday, with two children killed and 13 civilians wounded, security and medical officials said.

Fighting initially broke out in the Ramadi area on December 30, when security forces cleared a year-old Sunni Arab protest camp.

The violence spread to Fallujah, and militants moved in and seized the city and parts of Ramadi after security forces withdrew.