The blast took place in the mainly Shia town of Khalis, about 80km (50 miles) north of Baghdad, at about 16:30 GMT.

Earlier this month, a spate of attacks killed more than 100 people.

The situation in the country remains tense after elections in March, with no bloc having yet assembled a majority to form a government.

It is the deadliest attack since a double bombing on May 14, which killed 25 people and wounded 120.