BAGHDAD, Iraq — Bombs killed more than 60 people and wounded more than 200 yesterday in Baghdad and the northern oil center of Kirkuk — a dramatic escalation of violence as American and Iraqi forces crack down on Iraq’s most feared Shiite militia.

Prime Minister al-Maliki left yesterday for talks in Washington this week with President Bush to discuss sectarian violence, which has risen sharply since Iraq’s national unity government took office two months ago.

A suicide driver detonated a minivan at the entrance to a bustling market in Sadr City, the capital’s biggest Shiite district and stronghold of radical cleric Muqtada al-Sadr and his Mahdi Army militia.

At least 34 people were killed and 74 were wounded, the Iraqi army said in a statement. Eight more people died and about 20 were injured when a roadside bomb exploded two hours later at a municipal building in Sadr City about a half-mile from the car bombing, the army said.

In Kirkuk, 180 miles to the north, a car bomb detonated at midday near a courthouse. The courthouse is located among a cluster of wooden shops and stalls, many of which burst into flames, engulfing the warren of crowded streets in roiling black smoke.

Twenty people were killed and 159 were wounded, police said. The tally of injured was so high because many people were trampled as panic swept shoppers, police said. Others suffered burns when the initial blast triggered secondary explosions in shops that sold chemicals and flammable liquids, police said.

Separately, the American military has dismissed all charges against a Pennsylvania National Guardsman accused of killing an unarmed Iraq civilian near Ramadi, finding that the soldier had reason to believe the man had a weapon.

Specialist Nathan Lynn, 21, of South Williamsport, Pa., was accused of voluntary manslaughter and conspiracy to obstruct justice over the death of Gani Ahmed Zaben during a February 15 raid on a suspect’s house.