The past few weeks have seen a series of clashes between NATO troops and Albanian separatist forces in areas close to the border with Serbia. Fighting has occurred in both the ethnically partitioned Kosovan town of Mitrovica and across the border in Serbia in the Presevo Valley.

The fighting in Presevo involves the Liberation Army of Presevo, Medvedja and Bujanovac, (UCPMB). The organisation is named after three predominantly ethnic Albanian towns that the insurgents want incorporated within Kosovo, as part of a drive to secure formal independence for the whole province and its eventual merger with Albania.

Although controlled by the UN and NATO under the terms of the 1999 peace agreement that ended the bombing of Yugoslavia, Kosovo formally remains part of Serbia, the main component of the Federal Republic of Yugoslavia (FRY). UCPMB fighters, who emerged last February from the ranks of the Kosova Liberation Army (KLA), operate in the three-mile wide “Ground Safety Zone” between Kosovo and the rest of Serbia. Yugoslav military forces are not allowed to enter the zone, except for lightly armed police. This has enabled the UCPMB to operate inside the zone with virtual impunity. The government in Belgrade considers the area strategic because it controls the land routes south to Macedonia and Greece.

The ethnic Albanian insurgents killed four Serb police officers in November and overran an extensive trench network constructed by Serb forces. Four Serbs were abducted in December but were released after NATO intervened. Six more Serbs were taken hostage more recently, and were again released after NATO intervention. Nine members of the UCPMB were detained by British troops when they tried to enter Kosovo from the Presevo Valley at the beginning of this year. A NATO statement said 22 rifles were confiscated. Lieutenant-Colonel Stephen Kilpatrick, the commander of the British unit, said another four men-also suspects but unarmed and in civilian clothing-were detained separately.

Since the Western powers took over the running of Kosovo in June 1999, the province has been the scene of countless attacks on Serbs and members of other minorities. International officials have also expressed concern about political killings among Albanians.

In mid January, Bernard Kouchner, in a farewell speech before stepping down as UN governor in Kosovo, warned his overwhelmingly Albanian audience that the violence could cost Kosovo dear in terms of Western sympathy and aid. "As one friend to another, I want to warn you that you are in danger... In the eyes of the outside world, the victims, in a way, have become the oppressors."

Less than a week later, however, a Serb policeman was wounded during a shooting incident in the Ground Safety Zone near Presevo.

At the end of January, hundreds of Albanians clashed with French troops in Mitrovica, in some of the worst violence for several months. K-for riot troops serving with NATO used stun grenades and tear gas to disperse the crowds. At least 18 people were treated for injuries. The violence followed the killing of a 15-year-old Albanian boy in a grenade attack in the Serb dominated north of the city on January 29.

The protest started with a peaceful demonstration by students outside the city's municipal headquarters. As more people gathered, the crowd broke through flimsy barriers and ran past French troops towards the bridge over the River Ibar, which runs between the Serb and Albanian districts of Mitrovica. Some youths threw rocks and soldiers responded by firing tear gas and throwing stun grenades. Two armoured vehicles were ransacked and set alight. A crowd of Serbs gathered on the other side of the river, and taunted the Albanians, but most of the anger was aimed at the French who are many Albanians regard as pro-Serbian.

Away from the bridge, a French military base in a former hotel in the south of the city came under a hail of stones. Soldiers drew up in a line of armoured personnel carriers and fired stun grenades in response. Such was the level of hostility towards the French troops that Italian soldiers later replaced them.

On February 5, the UCPMB fired mortar shells and small arms in an overnight attack against government positions in southern Serbia. At a training camp in the area, the two men in charge of a UCPMB brigade claimed to have trained up to 600 volunteers in 10 months. One told the media, " War will happen when everything else fails...Currently we are under a peace agreement...All the same, our warriors are getting trained and armed to be ready for an offensive to get the Serbs out of this area." US army officers have estimated that the actual number of UCPMB fighters in the 25-mile Presevo corridor is between 500 and 800, but the UCPMB say the figure is closer to 3,000.