A suicide car bomb near an army base in north Iraq killed at least four people on Monday, security officials said, the latest in an uptick in violence nationwide amid a political crisis.

The blast struck in the al-Muthanna area of Mosul, which lies 350 kilometres (220 miles) north of Baghdad, killing four people and wounding five others, according to security and medical officials.

Also north of the capital, a roadside bomb killed a policeman and wounded two others in the disputed city of Kirkuk, while a police brigadier general was badly wounded by a magnetic "sticky bomb" attached to his car, officials said.

No organisation immediately claimed responsibility for the attacks, but Sunni militants including Al-Qaeda's front group often target security forces and officials in a bid to destabilise the government and push the country back towards the sectarian war that blighted it from 2005 to 2008.

The violence is the latest in a wave of unrest including car bombs and suicide attacks after weeks of rallies in Sunni-majority areas calling for the ouster of Iraqi Prime Minister Nuri al-Maliki.