Tens of thousands of Pakistanis have joined marches in cities nationwide to protest against a possible US-led war against Iraq and US bombing on the border with Afghanistan.

The protests were called by an alliance of six religious parties that made significant gains in October elections.

If the US attacks Iraq there will be open war here. No American will be safe here Alliance leader Maulana Samiul Haq

Some of the biggest rallies were in towns and cities bordering Afghanistan.

In Peshawar, several thousand people took to the streets chanting ''Down with America'' and "Long Live Saddam Hussein."

Numbers were expected to swell as the demonstrations developed during the day.

FBI presence

The protesters heard Islamic leaders denounce the American military build-up against Iraq.

The weekend bombing exacerbated anti-US feeling

One of them, Maulana Fazlur Rehman, said: ''The American attack on Iraq will be an attack on the Islamic world. If today we cannot stop America from attacking Iraq, then tomorrow they will attack Iran, and then it could be Pakistan."

The demonstrators also denounced the presence of FBI officials in Pakistan, and the American military involvement in Afghanistan.

Rallies were held in dozens of cities but remained mainly peaceful amid a large presence of riot police.

In Islamabad, about 400 people rallied outside the Red Mosque, some carrying banners reading ''American Terrorism'' and ''Stop the Holocaust Against Muslims''.

An alliance leader, Maulana Samiul Haq, said: ''If the US attacks Iraq there will be open war here. No American will be safe here."

Assembly motion

The anti-US feeling has been exacerbated by a border incident on Sunday.

Pakistan's Government said a US bomb had fallen on its territory near the border with Afghanistan, contradicting US reports that it had fallen inside Afghanistan.

The bomb was dropped after the US military in Afghanistan said a patrol came under fire near the town of Shkin, injuring one American soldier.

It said a Pakistan guard had opened fire after being asked to return to his side of the border.

The US authorities said later they had a long-standing policy, with the express consent of the government of Pakistan, to cross from Afghanistan in pursuit of fugitive Taleban or al-Qaeda militants.

The presence of these American forces is against the sovereignty of Pakistan. They should leave Islamic leader Zarnoor Afridi

Islamabad has made no official comment on the US assertion.

The US warplane had bombed a disused school where the guard had taken refuge, reports from Pakistan said.

No-one was hurt in the raid, but it outraged legislators in the Islamist-ruled North-West Frontier Province.

The provincial assembly approved a unanimous motion on Wednesday condemning the bombing as a violation of airspace and sovereignty.