K-For will not tolerate Kosovo as a staging area for exporting violence

Nato spokesman

Nato's peace-keeping force in Kosovo "was involved in the discussions and process of working out the details of the ceasefire," K-For spokesman Flight-Lieutenant Mark Whitty told Reuters news agency.

Bozo Prelevic, one of Serbia's three interior ministers, said on Friday that if the Monday deadline were not met, Serbian police would return to the zone "with all available means".

Separatists blamed

A five-kilometre wide security zone on the Serbian side of the border was demilitarised under an accord signed between Nato and Yugoslavia last year.

Currently, only lightly armed Serbian police are allowed to patrol there.

But police there say they have come under attack in recent days from Albanian separatists.

Four policemen were reported killed and several others injured in the attacks on Tuesday and Wednesday.

Timeline

21 Nov - Armed Albanians infiltrate southern Serbia, engage police 22 Nov - Attempt on life of Yugoslav representative in Pristina 22 Nov - Bodies of Serbian policemen found in southern Serbia 22 Nov - Ten Albanians detained by K-For, ammunition lorry seized 23 Nov - K-For troops close border checkpoint 23 Nov - Moderate Albanian Xhemajl Mustafa shot dead in Pristina 24 Nov - K-For finds arms after mortar attack 24 Nov - Serbia gives K-For 72 hours to end attacks

K-For stepped up monitoring and boundary patrols after the attacks, which it blamed on the Albanian guerrillas.

But it also warned Belgrade not to send troops or special police into the border zone.

A spokeswoman for the UN High Commissioner for Refugees said the three days of fighting had forced about 600 ethnic Albanians living in the border zone to flee into Kosovo.

"After several months of no new arrivals of internally displaced persons, the security situation has deteriorated rapidly," Astrid van Genderen told journalists on Friday.

Around 70,000 ethnic Albanians live in the Presevo valley, still administered by Belgrade.

Guerrillas involved in the current fighting are believed to come from the Liberation Army of Presevo, Medvedja and Bujanovac (UCPMB), an offshoot of the Kosovo Liberation Army.

They are seeking to secede from Belgrade and include the region in an independent Kosovo.