A wave of violence across Iraq has killed at least 48 people, many of them in a series of attacks in the northern city of Mosul.

Twenty-eight people were killed in the city, which is populated mainly by Sunni Arabs, when four car bombs targeted the army and police on Monday, a police official told Al Jazeera, adding that a curfew had been imposed.

Three attackers were among the dead and about 80 people were wounded, the source said. 

Earlier in the day, car bombings hit two markets in central Iraq, killing at least 22 civilians and wounding 30 others, officials said.

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A police officer said three car bombs exploded virtually simultaneously, tearing through a wholesale vegetable and fruit market in the town of Jadidat al-Shatt in Diyala, just outside the provincial capital of Baquba, about 60km northeast of Baghdad.

The blasts left 13 dead and more than 50 wounded among the wreckage of fruit and vegetable stalls, local officials and police said.

Another car bomb hit a market in the religiously-mixed town of Taji, 20km north of Baghdad, killing at least eight more people, police and hospital sources said.

A car bomb also exploded at an army base south of Kirkuk, killing one soldier and wounding six others, security sources told Al Jazeera.

In Madaen town south of Baghdad, two bombs targeted a federal police checkpoint, killing three people and injuring 10 more, and in the Sadr neighbourhood in northern Baghdad a bomb exploded at a cafe, killing one and injuring eight.

No group claimed the attacks, but Iraq is facing a surge in sectarian violence that officials blame on Sunni fighters determined to drag the country into a civil war.

Growing violence has tracked rising political tensions between Shia leaders and minority Sunnis who feel their sect has been marginalised since the fall of Saddam Hussein after the 2003 US-led invasion.

According to the UN, at least 1,045 Iraqi civilians and security personnel were killed in May. The tally surpassed April's 712 killed.

Source: Al Jazeera and agencies