Speaking on German radio, Mr Petritsch also said the continuation of the monitoring effort by the Organisation for Security and Co-operation in Europe make military intervention unnecessary.

His remarks follow a warning by OSCE chief Bronislaw Geremek, who said that "if the bloodshed and violence escalate, OSCE will have to reconsider the forms of its activity in Kosovo".

The ethnic Albanian leader in Kosovo Ibrahim Rugova has meanwhile renewed calls for the deployment of monitors to be speeded up. He also urged for greater efforts, including Nato intervention, to stop what he called Serbia's policy of ethnic cleansing.

A ceasefire is currently holding in Kosovo after the OSCE persuaded both sides to respect a ceasefire.

This truce came after at least 13 people died in four days of clashes around the town of Podujevo.

But the KLA has warned that fighting could resume at any moment. One KLA leader told the BBC that there had been no formal agreement to lay down weapons.

The KLA, which is seeking independence for Kosovo from Belgrade, is maintaining its checkpoints on territory it holds.

Serbs seek protection

Serbian officials in Kosovo have sent an open letter to President Slobodan Milosevic, demanding better protection for ethnic Serbs, hundreds of whom have fled their homes during the current fighting.

The BBC Correspondent in Pristina, Jackie Rowland, says the letter presents Mr Milosevic with a dilemma, since reinforcing his military presence in Kosovo could put him at loggerheads with OSCE observers who are monitoring Belgrade's compliance with October's peace agreement.

Frustration

The OSCE head of mission in Kosovo, William Walker, said the temporary truce has allowed both Albanian and Serbian casualties to be taken out of the main area of fighting.

"Both sides are being relatively cautious," he said. "They are listening to us when we talk to them, and there's another local truce in the area holding for the last couple of hours as we try to extract people and talk some more.

"It is very frustrating. We wish we had more co-operation from both sides."

The latest clashes broke out as mourners buried an elderly Serb man killed by guerrillas in the village of Obrandza.

The OSCE blamed both sides for the worsening situation.

A statement said: "Contrary to the October agreements and commitments, Serbian forces have re-entered Kosovo and resumed repressive actions".

"At the same time, terrorist acts have been committed by armed groups of the Albanian population."

Christmas Eve attack

The region's fragile peace was shattered on Christmas Eve when the Serbs launched an offensive on villages around Podujevo.

The KLA responded by calling off its ceasefire.