A series of explosions was heard on the edge of the Yugoslav capital's central district, witnesses said, and Serbian television reported a factory making heating units had been hit in the suburb of Novi Beograd.

Earlier NATO missiles destroyed another bridge over the Danube river in Yugoslavia's second city, Novi Sad, over which civilian traffic was crossing, state media said. Seven people were reported injured.

The city's Petrovaradinski bridge was destroyed on Thursday, cutting the Orient Express railway route between Vienna and Belgrade and blocking barge traffic on Europe's longest river, the Danube. A third bridge remains.

Serbian news media also reported an attack on another Danube bridge further west at the Croatian border, saying it was damaged but notdestroyed.

Meanwhile, BBC broadcast what it said was an amateur film smuggled out of Kosovo, showing the bodies of men killed in atrocities in the southern Serbian province.

NATO said it was rethinking the role its troops might play in Kosovo when the time comes to escort refugees back to their homes.

The United States dismissed suggestions that NATO might fight its way into Kosovo because 11 days of air strikes had not prevented mass expulsions of ethnic Albanians by Serbian security forces.

But Britain's Sunday Times newspaper said the western powers were making plans for an invasion -- once Yugoslavia's armed forces were wiped out by air power.

US President Bill Clinton and British Prime Minister Tony Blair insisted NATO had sent a ``powerful message'' with the missile destruction of key police buildings in Belgrade yesterday -- the first blow at the heart of the Yugoslav capital.

From London, the British Broadcasting Corporation screened scenes last night from an amateur video which issaid appeared to show mass murder by Serbian forces in Kosovo.

British Foreign Secretary Robin Cook said the pictures underlined the justice of NATO bombing raids against Yugoslavia.

The amateur ethnic Albanian cameraman who smuggled the film out of Kosovo said it showed a massacre of men from his village, according to the BBC.

``Milaim Bellanica claims Serb forces executed the Kosovo Albanian men one by one after surrounding their homes,'' it said.

Bellanica was quoted as saying more than 100 ethnic Albanian villagers were killed when Serb forces shelled the area. ``The pictures show many of the bodies had bullet wounds to the back of the head or under the jaw,'' the BBC said.