Angry Pakistanis near the Afghan border threatened war against Americans, and police fired tear gas at protesters in the country's largest city as Muslim parties launched nationwide strikes Friday to protest Pakistan's support for Washington's campaign against terrorism.

The demonstrations were called throughout the country after Pakistani President Pervais Musharraf gave his support to U.S. efforts to apprehend Usama bin Laden and to break up bin Laden's suspected terrorist network operating from neighboring Afghanistan.

Pakistan's support for U.S. forces is critical to the American campaign because of its strategic location and its ties to Afghanistan's hardline Taliban regime, which has sheltered bin Laden, the chief suspect in the Sept. 11 terrorist attacks in New York and Washington.

Hard-line Islamic parties in Pakistan oppose Musharraf's stand, and the outcome of their call for Friday's nationwide strike was to serve as a barometer of public support for Musharraf in this heavily Islamic country of 140 million people.

The extent of the protests was unclear because starting times varied from city to city. Many shops were closed and transport suspended, in part out of fear of violence. Friday is the Muslim day of prayer, and police braced for more demonstrations after midday services at mosques.

In the northwestern border city of Peshawar, thousands of people took to the streets, screaming anti-U.S. and anti-Pakistan slogans. They gathered in front of the main mosque where their religious leaders made speeches over a microphone supporting bin Laden and the hard-line Muslim Taliban leadership that has protected him and his followers in Afghanistan for years.

Jamming the streets of the city, where all markets and stores were closed, the protesters carried a life-size effigy of President Bush, and shouted slogans such as "Long live Usama."

"We will fight until the death and destruction of the United States," said one sign. "Crush America and Bush" said another.

No violence was reported, as heavily armed police stood by and watched.

In Karachi, the country's biggest city and commercial hub, police fired tear gas and beat people with iron-tipped sticks to disperse small demonstrations by people who pelted vehicles with stones and blocked roads. At least 70 demonstrators were arrested, police said.

In the largest protest, about 1,500 Afghan refugees clashed with police in Karachi's Sohrab Goth neighborhood. The Afghans burned tires and attacked the few vehicles on the streets.

Major markets in the city were closed.

In Lahore, a city east of Islamabad, most main markets remained closed, and people were expected to join an anti-government march later Friday after services at the main mosque.

In Islamabad, the capital, the government ordered schools and offices closed for their own safety. No protests were immediately held.

In the southwestern city of Quetta, most shops and markets were closed, and police dressed in riot gear guarded the streets, ordering foreign journalists to stay in their hotels. But no protests were reported by midday, several hours before services were to begin at local mosques.

The protests coincided with a Pakistani newspaper report Friday that bin Laden has left Afghanistan. The English language daily, The News of Islamabad, quoted unidentified sources close to the Taliban as saying bin Laden left the country on Monday for an unknown location. The report could not be confirmed.

On Thursday, a grand Islamic council in Afghanistan called to meet by the Taliban leadership asked bin Laden to leave voluntarily.

Also Friday, a top Pakistani official said a high-powered U.S. team of military experts and State Department officials will arrive in Pakistan next week to work out the specifics of cooperation in an anticipated U.S. strike against Afghanistan.

So far, Pakistan has not received any word on the timing of a possible attack on next-door Afghanistan and no senior U.S. official has arrived in Pakistan for talks on cooperation, said the official, who is involved in the talks with the United States.