BAGHDAD - A suicide bomber driving a car packed with explosives detonated the vehicle near an Iraqi military base as soldiers changed shifts north of Baghdad on Tuesday, killing at least 33 people and wounding 56, according to authorities.

The blast struck about midday as troops were leaving the base in Taji, 12 miles north of the capital, police said.

Twenty-two soldiers were among the dead, and several vehicles were damaged, they said.

The casualty toll was high because the attacker blew up the car while large numbers of soldiers were walking to and from a parking area for waiting minibuses that take them to work, officials said.

There was no immediate claim of responsibility, though suicide car bombings are a favorite tactic of Sunni militant groups such as al-Qaida.

Insurgents frequently target members of the country's security forces in an effort to undermine confidence in the Shiite-led government.

Although violence has ebbed in Iraq since the height of the insurgency, attacks still occur frequently.

Also Tuesday, Iraq's Cabinet voted to do away with a major social safety net program and instead provide cash payments directly to citizens, government spokesman Ali al-Dabbagh said.

The reform would bring an end to food ration cards that many Iraqis use to buy basic, highly subsidized foodstuffs such as flour and rice.