Karachi, Dec. 28 (Reuters): Troops were called out today to quell some of Pakistan’s worst political violence in years sparked by Benazir Bhutto’s assassination .

Officials said 31 people, including four policemen, had been killed since the former Prime Minister was murdered yesterday.

Most of the dead were killed in Sindh in the south, Bhutto’s home province and main power base. Troops were deployed in several parts of Sindh, officials said, and banks and schools were closed across the country.

In Hyderabad, police and witnesses said protesters had set fire to about 25 banks, to 100 vehicles and to foreign fast-food outlets, despite orders to the police and paramilitary forces to shoot violent protesters on sight. Several train coaches were also torched.

Interior ministry spokesman Javed Iqbal Cheema told a news conference that “vested groups” and criminals were taking advantage of the situation to loot and rob banks.

Officials had said they feared the disturbances would intensify after Bhutto’s funeral at her family’s ancestral home in Sindh.

In a suspected Islamic militant attack in the northwesterly Swat valley, where the army has been fighting pro-Taliban forces, a blast at an election meeting of the Pakistan Muslim League (Q) party killed six persons including an election candidate, police said. The party backs President Pervez Musharraf.