MAIDUGURI, Nigeria -- Nigerian Muslims protesting caricatures of the Prophet Muhammad attacked Christians and burned churches Saturday, killing at least 15 people in the deadliest confrontation yet in the whirlwind of Muslim anger over the drawings.

It was the first major protest to erupt over the issue in Africa's most populous nation. An Associated Press reporter saw mobs of Muslim protesters swarm through the city center with machetes, sticks and iron rods. One group threw a tire around a man, poured gas on him and set him ablaze.

In Libya, the parliament suspended the interior minister after at least 11 people died when his security forces attacked rioters who torched the Italian consulate in Benghazi.

Right-wing Italian Reforms Minister Roberto Calderoli resigned under pressure, accused of fueling the fury in Benghazi by wearing a T-shirt emblazoned with one of the offending cartoons, first published nearly five months ago in a Danish newspaper.

Danish church officials met with a top Muslim cleric in Cairo, meanwhile, but made no significant headway in defusing the conflict.

And in what has become a daily event, tens of thousands of Muslims protested -- this time in Britain, Pakistan and Austria -- to denounce the perceived insult.

But it was in Nigeria, where mutual suspicions between Christians and Muslims have led to thousands of deaths in recent years, that tensions boiled over into sectarian violence.

Thousands of rioters burned 15 churches in Maiduguri in a three-hour rampage before troops and police reinforcements restored order, Nigerian police spokesman Haz Iwendi said.

Chima Ezeoke, a Christian Maiduguri resident, said protesters attacked and looted shops owned by minority Christians.

"Most of the dead were Christians beaten to death on the streets by the rioters," Ezeoke said. Witnesses said three children and a priest were among those killed.