Twin car bombings in the northern Iraqi city of Mosul and an attack by eight gunmen on the home of a school teacher in the centre of the country left at least 10 people dead, government officials said.

Violence is raking Iraq as the Shia-led government and other political factions are debating a request for some American forces to remain in the country beyond the December 31 deadline for all US troops to withdraw after more than eight years.

While violence is well below what it had been during intense Shia-Sunni sectarian fighting in 2006 and 2007, opposition fighters are again stepping up deadly attacks around the country. That has led to concerns about what happens when the 47,000 US troops still in the country are withdrawn.

Police and hospital officials in Mosul said two car bombs exploded in quick succession, killing six people. At least one of the bombs seemed aimed at a police patrol.

Mosul is Iraq's third largest city, 360km northwest of Baghdad. It has been one of the most stubborn strongholds of resistance.

Abdul-Rahim al-Shimmari, a member of the provincial council, said 52 people were wounded in the blast.

The force of the explosion shattered the windows and mirrors in a nearby barber shop, and caused the false ceiling to collapse.

"Fortunately, none of us were wounded, but one of my customers, whose hair was half cut, ran away out of fear," the owner, Mahir al-Abbawi, said.

Security forces opened fire randomly in all directions after the first explosion to prevent those who rushed to help at the scene, he said.

"After about four minutes, we saw a ball of fire coming out of another car that was about 10 meters away from the first explosion," he added.

Al-Abbawi said he could see people bleeding and women and children screaming and crying.

In the other attack, eight gunmen stormed the house of a school teacher overnight and killed his three sons and daughter, Mohammed al-Asi, the spokesperson for central Salahuddin province, said.

He said the gunmen were in a minibus and fled after the midnight attack in a village outside of Tikrit. Authorities were investigating the motive behind the killing to see whether it was an act of insurgents or tribal conflict, he added.

Tikrit is Saddam Hussein's hometown and is located 130km north of Baghdad.

Source: Agencies