BAQUBA, Iraq (AFP) - A bombing killed three children at a popular swimming area in Iraq on Wednesday, following a similar attack two days before, the police and a doctor said.

The bomb was planted near Al-Shakha river in the Muqdadiyah area north-east of Baghdad.

The explosion came after mortar rounds struck a swimming area on the Tigris river north of the capital on Monday, killing four people, including a child.

Muqdadiyah has been hit by several attacks in recent days, including a bomb targeting worshippers leaving a Sunni mosque on Tuesday, killing four people and wounding 15.

The children killed on Wednesday were also Sunni.

A plague of sectarian violence killed tens of thousands of people in Iraq in past years, and there are persistent fears that tensions will again boil over into all-out conflict.

In the northern city of Kirkuk on Wednesday, two bombings wounded two members of the Kurdish peshmerga security forces, a senior officer and a doctor said.

Kirkuk is part of a swathe of northern territory that the autonomous Kurdistan region wants to incorporate over the strong objections of the federal government in Baghdad - a dispute that officials and diplomats warn is one of the main threats to Iraq's long-term stability.

Wednesday's attacks come as Iraq struggles with its worst violence since 2008.

More than 2,600 people have been killed so far this year, according to AFP figures based on security and medical sources.