An American state department spokesman said there should be no doubt of Nato's resolve.

The Nato Secretary-General, Javier Solana, said it would not tolerate a return to all-out fighting and repression in Kosovo.

The BBC's Orin Gordon rounds up coverage of the massacre and the international response to it

President Clinton and the head of the international observer mission in Kosovo both blamed Serbian forces for the killings.

Mr Clinton said it was a clear violation of commitments made to Nato by President Slobodan Milosevic for a peaceful solution in Kosovo.

Those killed in the village of Racak, south of Pristina, were mostly men who had been rounded up and shot at close range. Some had been mutilated.

International monitors say they have also seen the bodies of three women and a 12-year-old boy.

War crimes inquiry

The massacre has prompted the International War Crimes Tribunal on the former Yugoslavia to open an urgent inquiry.

The Tribunal's chief prosecutor, Louise Arbour, is to leave for Kosovo within the next two days to investigate the mass killings.

Local villagers say the slaughter of the victims, mostly men aged between 18 and 65, was carried out by Serb forces who rounded the group up on Friday night.

Serbia dismissed reports of the massacre as media manipulation and said its forces came under attack while they were investigating the murder of a policeman.

The Kosovar Albanian political leader, Ibrahim Rugova, has declared Sunday a day of mourning in Kosovo.

Killings 'unacceptable'

Germany, which currently holds the presidency of the European Union, said the international community would not accept such acts of persecution and murder.

Jacky Rowland in Pristina: This is a blatant challenge to the authority of ceasefire monitors in Kosovo

In Paris, the French Foreign Ministry expressed disgust at the massacre and called for a meeting of the Organisation for Security and Cooperation in Europe (OSCE) to investigate who was responsible.

UK Foreign Secretary, Robin Cook, said: "Those responsible for the crimes must be held to account before international justice."

BBC World Affairs correspondent David Loyn: "This was an horrendous event"

The feelings of anger were echoed on the ground in the region.

The US special envoy, Richard Holbrooke, condemned the killings, saying they were the most serious offence since the outbreak of the violence which has plagued the province in recent months.

Mr Holbrooke said the Yugoslav authorities should punish those responsible for the crimes themselves.

The head of the international monitors in Kosovo condemned the massacre as an "unspeakable atrocity" and "a crime very much against humanity".