Pakistan has handed over to US authorities about 20 Arabs arrested last week in raids on suspected al Qaida hideouts, a senior intelligence official said today.

Authorities in Pakistan arrested hundreds of militant Muslims and sealed an entire city today after leaders of an influential Islamic political party vowed to attack an air base where US personnel were said to be working.

Police and paramilitary troops fired tear gas today to repel hundreds of angry militant Muslims marching on a southern Pakistani air base where US personnel are reportedly working, the authorities said.

Thousands of Islamic militants clashed with police across Pakistan today, hurling stones, burning cars and setting a fast-food restaurant on fire.