At least two people have been killed in an apparent suicide bombing targeting a police station on the northern outskirts of Baghdad.

Seventeen people were wounded in the attack in the town of Tarmiya, interior ministry officials said on Sunday.

"A suicide bomber detonated his explosives vest at the entrance to a police station, killing two civilians and wounding 17 people, including nine policemen," an official said.

A spokesman for Baghdad Operations Command, which co-ordinates security forces in the Iraqi capital, told the Reuters news agency that the attack was carried out by a bomber in a wheelchair. He said he expected the death toll to rise.

Sunday's attack follows three bombings in southwest Baghdad on Thursday which killed at least 23 people and injured at least 100 more at a crowded market.

Attacks against Iraqi security forces have been increasing as the country's army and police prepare to take total responsibility for security ahead of a full withdrawal of US troops by December.

The latest attacks came as thousands of Shia Muslim pilgrims headed to the holy Shrine of Imam Moussa Kadim to commemorate the anniversary of his death in northern Baghdad.

The shrine in the neighbourhood of Kazimiyah is the capital's most important site of pilgrimage for Shias. The ceremonies will continue until June 28.

Source: Al Jazeera and agencies