The Pakistani government has warned it will not tolerate violent demonstrations.
Armed troops in military vehicles are patrolling streets in major Pakistani cities ahead of the anti-American demonstrations. Activists of Islamic parties supporting Afghanistan's Taleban rulers are expected to take to the streets after prayers on Friday, the Muslim holy day.
The heavy security in the capital, Islamabad has included erecting sandbag-protected army posts near government buildings and diplomatic missions.
Tension is particularly high in southwestern border town of Quetta, where five people were killed earlier this week when a large demonstration turned violent. Pakistani officials have dismissed the anti- U.S. demonstrations as a fringe movement. Aziz Khan is a spokesman for Pakistan's Foreign Ministry.
"In case of any small minority trying to launch any protest, the law and order machinery of the government of Pakistan is firmly in a position to control it, " says Aziz Khan, a spokesman for Pakistan's Foreign Ministry.
Ever since the U.S. led air attacks in Afghanistan began Sunday, leading Islamic parties in Pakistan have held almost daily protest rallies. They are demanding removal of President General Pervez Musharraf because of his support for the U.S. military campaign. The strikes are aimed at flushing out suspected terrorist Osama bin Laden and his followers hiding in Afghanistan. The ruling Taleban is also under attack for sheltering the Saudi fugitive.
Pakistan's largest Islamic party, Jamaat-i-Islami, has threatened to launch a nationwide campaign from next Monday to force the military government to change its support for the American attacks in Afghanistan or give up power.