Yugoslavia says it will move into the "dangerous" border zone

The Macedonian authorities have yet again closed all the border crossings with Kosovo to prevent incursions.

In Serbia, officials said that a policeman had died after a mortar attack by ethnic Albanian guerrillas on the village of Lucane in southern Serbia.

The incidents come as Nato considers deploying troops along the volatile Macedonian border with Kosovo.

The military alliance has already decided to allow Yugoslav troops back into part of the buffer zone alongside Macedonia which divides Kosovo from the rest of Serbia.

We want to prevent what can be limited, localised skirmishes becoming bigger or spilling over into the wider region

Nato chief Lord Robertson

Nato Secretary-General Lord Robertson said: "We want to prevent what can be limited, localised skirmishes becoming bigger or spilling over into the wider region."

Yugoslav President Vojislav Kostunica accepted the offer to move in to what he called a "very dangerous" area, but said it highlighted the failure of Nato to secure the zone.

"This is maybe one more proof of how inefficient in all these years... K-For has been," he said.

The rebels have warned that opening the zone to Yugoslav forces will lead to a worsening of the violence.

The actions of rebels, who want to unite parts of Serbia and Macedonia where ethnic Albanians live, have attracted international condemnation.

Albanian President Rexhep Mejdani has described their activities as "totally unacceptable".