The French-based charity, which has two teams working in Kosovo, says Serb forces in the province killed villagers and set fire to their homes in a shelling attack this week.

Nato decided earlier this week that Yugoslav President Slobodan Milosevic had withdrawn enough forces from the province by a 27 October deadline to avert threatened air strikes.

But Médecins du Monde disputed Nato's assertion.

"Serb forces are still on the ground, the guns and tanks are still there. Special forces remain in the area instilling terror in the people," said Director General Michel Brugier.

Another senior staff member, Olivier Brochu, said special Serb forces were still hiding in the woods - and that one of his teams had seen Serb artillery bombard a small village in south-western Kosovo.

"Our people saw the village in flames. It has been destroyed. There were a lot of deaths," he said.

Refugees 'have nowhere to go'

Doctors working with the charity agreed that Serbian troops had allowed free movement along major roads, and had lifted many of their checkpoints.

Returns to find Serbs still close to village

But they said this only encouraged tens of thousands of refugees, who had fled their villages earlier this year, to head home, when in fact their villages had been destroyed.

"They have nowhere to go. All their houses have been destroyed, their animals killed," Mr Brochu said.

"What are they expected to do? Between 70-80% of villages south-west of Pristina have been destroyed.

The organisation also disputed reports about improving conditions for Kosovar Albanian refugees, saying 50,000 were still in tents in appalling conditions.

The charity criticised Nato's decision not to go ahead with air strikes, and called for the team of 2,000 international monitors to take up their positions immediately.