BAGHDAD - A wave of violence across Iraq on Monday killed 61 people, nearly half of them in a series of attacks in the northern city of Mosul, officials said.

In Mosul, which is populated mainly by Sunni Arabs, 29 people were killed when five car bombs targeted the army and police, the officials said, adding a curfew had been imposed in the city. "We have received many corpses," said Anwar al-Juburi, a doctor at Mosul General Hospital. "Most of them were members of the security forces."

According to the doctor and an army brigadier general, who spoke on condition of anonymity, at least 29 people were killed and 80 others wounded in the city.

Mosul, and the surrounding province of Nineveh of which it is the capital, remain one of the most violent and unstable parts of Iraq.

It is one of several Sunni-majority areas of the country that have seen months of anti-government protests, with the community decrying alleged targeting at the hands of the Shiite-led authorities.

Attacks in the northern cities of Kirkuk, Tikrit and Tuz Khurmatu, meanwhile, left eight other people dead.

And explosions just north of Baghdad in Taji and neighbouring Diyala province, killed a further 20 people, while a suicide bombing targeting security forces killed four people.

The latest attacks are part of a spike in nationwide violence that last month left more than 1,000 people dead according to the United Nations, the highest such toll since 2008, sparking fears of a revival of the all-out sectarian war that blighted Iraq in 2006 and 2007.