Stephen Gibbs reports: Further confirmation that the informal truce is not holding

The visit comes as UN Secretary General Kofi Annan warned that the province faces all-out war in 1999 unless peace efforts are redoubled.

US State Department spokesman James Foley said Mr Holbrooke's meeting with Mr Milosevic would "drive home some home truths" about the need for full implementation of Serbian commitments under UN Security Council resolutions, "and the need for progress on the negotiating front".

Informal truce

In October Mr Holbrooke brokered an informal truce in Kosovo and persuaded the Serbian president to withdraw most of his forces from the province under the threat of Nato airstrikes.

But many Serb forces remain and Mr Milosevic says he cannot withdraw completely for fear of handing over the province to ethnic Albanian rebels with dangerous consequences for the province's Serbian minority.

On Monday there were renewed clashes in the province when Serbian forces killed at least 30 ethnic Albanians and injured another 12 in the worst violence since the ceasefire was agreed.

Border clash

Jackie Rowland in Belgrade: "No casualties on the Yugoslav side"

Serbian border guards reportedly encountered an armed group wearing uniforms of the Kosovo Liberation Army, trying to enter the province illegally from Albania. According to the Serbian Ministry of Information, the shoot-out happened on Monday near the border outposts of Gorozup and Liken southwest of Pristina.

Large quantities of weapons and supplies were also reported to have been seized.

The clashes came as a US envoy to Kosovo resumed talks on Monday with the province's ethnic Albanian negotiators.