The US Defense Department said Belgrade had deployed at least 4,500 troops on the border of the province, backed by tanks, artillery, and armoured personnel carriers. At the same time, 13 tanks left the main barracks in the province's capital, Pristina, yesterday to join about 30 already stationed in the Vucitrn area, north of Pristina.
Eight employees of the Organisation for Security and Cooperation in Europe (OSCE), meanwhile, were forced to spend the night in their cars after being prevented from entering Kosovo from Macedonia. "It's tense," said Beatrice Lacoste, a spokesperson. "They were being held - they can't go to Kosovo." At least one of the monitors is British.
The moves to block the monitors fed speculation that the Serbs are planning attacks on Kosovo villages as part of a campaign against "terrorists" seeking independence from Serbia.
In Belgrade, the Yugoslav army said its burst of activity was a "winter training exercise".
Most observers said they believe the army aims to drive the Kosovo Liberation Army (KLA) from Vucitrn, which has been the scene of several armed skirmishes this week.
A KLA spokesman told Reuters news agency: "They say they are on field manoeuvres, but what army do you know goes on manoeuvres during a war? Obviously they are looking to attack our positions to push us back."
The KLA moved into the area in October. Serbs have recently been leaving en masse, after attacks on ethnically mixed villages and a rash of shootings this week in which one Serb was killed.
Already the army's activity has sent about 4,000 Albanians fleeing from their villages, according to aid agencies in Kosovo. Massacres of Albanian civilians at Racak and elsewhere have made the Serb military an object of terror to the province's non-Serb majority.
The Albanian government complained yesterday to the Nato secretary general, Javier Solana, that Serbia was engineering a confrontation with the Kosovars to sabotage peace talks, which are due to restart on 15 March.
The last round of talks ended inconclusively in Rambouillet, near Paris, on Tuesday. "Belgrade is sending troops massively into the region in preparation for a general offensive against Kosovo," the Albanians said.
From Spain, Mr Solana warned Yugoslavia against trying to alter the military balance on the ground before 15 March. "These weeks are to consolidate peace, not to take advantage and make any change in the situation." he said, although he did not reveal what measures Nato would take if the Serbs did attack.Reuse content