A BBC correspondent in Belgrade, Nick Thorpe, says that while movements and concentrations of military hardware are kept secret, top generals have been touring the country, addressing officers and military cadets in an attempt to lift morale.

General Nebojsa Pavkovic, commander of the Third Army, whose zone of operations includes Kosovo, has threatened an all-out assault against the ethnic Albanian guerrillas if Nato air strikes start.

Nato forces could be 'legitimate targets'

Orla Guerin in Kosovo: "There is growing anxiety here"

According to sources close to the Yugoslav army, any Nato forces within range of their planes and missiles in Macedonia, Bosnia or on ships in the Adriatic could be considered legitimate targets, even though this could in turn provoke a massive Nato response.

Other commentators argue that the first pinprick attacks against air defence systems would be enough to force President Milosevic to sign the Kosovo agreement.

Defence Correspondent Jonathan Marcus: "Forces massing in and around Kosovo"

For ordinary people one tangible effect of the increased alert of the armed forces is a shortage of diesel fuel, which threatens the planting of the fields this spring.

Another is that conscripts who have already served their full military service have been ordered to stay in the army another month.

Serb forces attack

Serb forces have been bombarding Kosovo rebel positions this week, and ethnic Albanian villages have been looted.

The villages of Glavotina, Strovce and Bencuk, north of Kosovo's regional capital, Pristina, were attacked with heavy gunfire.

A BBC correspondent saw Serbs raze to the ground another ethnic Albanian village.

Thousands of people have fled the fighting since the peace talks resumed in Paris on Monday.

The US has said the Yugoslav military has been pouring thousands of troops and heavy arms into Kosovo in preparation for war - with up to 21,000 soldiers on the border and 18,000 in the province.

International monitors in Pristina said the Yugoslav army had moved at least eight of its most modern tanks into Kosovo for the first time since the verification mission began last year.

They said the Yugoslav army had been bringing in the new weaponry in violation of international agreements.

The US defence department also said the Serbs had been moving air defences to make them less vulnerable.

Nato has threatened military strikes if the Serbs do not sign up to the internationally-brokered peace plan, which has been signed by the ethnic Albanians.