Insurgents stepped up attacks on Iraqi security forces on Monday with six car bombings and a roadside bomb blast, killing at least 17 policemen.

A suicide car bomber targeted a group of Iraqi police recruits in the northern Kurdish city of Arbil, killing 13 people and wounding more than 100 others.

The attacker broke into a courtyard where some 200 traffic police recruits gathered for training and detonated his car at about 8:00 a.m. (0400 GMT).

"13 people were killed and about 107 wounded," Jamal Abdul Hamid, health minister of the autonomous Kurdish government, told reporters.

In Baghdad, four car bombs targeting police forces exploded simultaneously early on Monday, according to a statement by the Iraqi ministry of defense.

"Two car bombs detonated at 5:30 a.m. (0130 GMT) at the headquarters of the First Brigade of the Police Commandos, near Nussur Square (in western Baghdad)," the statement said.

Fierce clashes broke out with "terrorists wearing national guards uniform" afterwards, it said.

Meanwhile, another two car bombs hit Baiyaa police station after being pounded by mortars and small arms gunfire, the defense ministry said, without giving casualties.

Two hours later, a roadside bomb struck a police patrol in Baghdad's Mansur district, killing four policemen and destroying their vehicle, the statement said.

A sixth car bomb hit a police checkpoint on the main road to Baghdad's international airport at about 1:45 p.m. (0945 GMT), causing several casualties, a police officer told Xinhua on condition of anonymity.

The US and Iraqi forces cordoned off the area after the blast.

Insurgents frequently attack US and Iraqi security forces on the main road to Baghdad International Airport, which has become the most dangerous road in the violence-torn country.

The past month has seen Iraq's security forces launching Operation Lightning, its biggest security offensive against insurgents in and around the capital with 40,000 troops involved.

It was part of efforts designed to curb the surging violence which have killed more than 1,000 people across the country since a Shiite-dominated government was formed on April 28.

Source: Xinhua