Police opened fire on protesters in an Afghanistan city during a second day of anti-American demonstrations that ended with four dead and dozens wounded.

The demonstrations Wednesday followed a report that American interrogators in the US prison camp at Guantanamo Bay, Cuba, had desecrated the Koran.

American troops stationed in the conservative Muslim city of Jalalabad were confined to base during the protest.

Government offices in Jalalabad were set on fire, shops looted, and United Nations buildings and diplomatic missions attacked as thousands took to the streets.

``Police had to open fire on the protesters,'' said provincial police chief Hazrat Ali.

``They were destroying the city.''

The province's health chief, Fazel Mohammad Ibrahimi, said that along with the four dead there were 52 demonstrators wounded.

About 1,000 students demonstrated in nearby Laghman province, while in Khost city, protesters burnt a picture of US President George W Bush along with a US flag.

There was also a report of a protest in Wardak province. The demonstrations followed a Newsweek report that investigators probing abuses at the US military prison in Guantanamo Bay had discovered that interrogators ``had placed Korans on toilets, and in at least one case flushed a holy book down the toilet.''

Washington-backed President Hamid Karzai said of the demonstrations during a visit to NATO headquarters in Brussels: ``It shows Afghan institutions are not yet ready to handle protests.''

The US commands a foreign force in Afghanistan of about 18,300, most of them American, fighting Taleban insurgents and hunting Taleban and al-Qaeda leaders, including Osama bin Laden, architect of the September 11, 2001, attacks.

The United States is holding more than 500 prisoners from its ``war on terror'' at its base on Cuba. Many of them were detained in Afghanistan after US-led troops overthrew the Taleban government in late 2001.

About 2,000 students chanting ``Death to America'' protested in Jalalabad Tuesday demanding an apology and punishment for those involved in the reported incident.

But many more turned out Wednesday, with ``ordinary residents'' also taking part, said a witness who estimated that more than 5,000 people were involved.

The protesters also denounced Karzai, destroying a big portrait of him and shouting ``Death to America's allies'' and ''Death to Karzai'' as well as ``Death to Bush.'' ``We don't want America, we don't want Karzai, we want Islam,'' they shouted.

Cars were smashed, shops ransacked and government buildings torched. Protesters also looted the Pakistani consulate. An Indian mission was also attacked.

UN cars were set on fire and two UN offices attacked but not seriously damaged, said spokeswoman Ariane Quentier. All staff had been accounted for and confined to safe areas.

In Kabul, a US military spokesman said the reported desecration of the Koran was being taken seriously.

``We are investigating this and other complaints to see if in fact it has happened and, if so, to put in place procedures so that it will not happen again,'' he said. Karzai is due to visit the United States this month.