Kerem Lawton: Died from shrapnel wounds

Both the Macedonian army and the rebels have denied responsibility for the mortar attack on the village of Krivenik, which lies just one kilometre inside Kosovo.

The shelling came as Nato-led international peacekeepers stepped up their patrols of the Kosovo-Macedonia border.

Macedonian troops are trying to drive the rebels from their strongholds in mountainous terrain close to the border.

Rebels hidden

Krivenik is separated by a mountainous ridge from Gracani, the Macedonian hamlet which is the focus of the current fighting.

American soldiers from the Nato-led force treated the casualties at a hastily-erected field hospital.

Macedonian army

Manpower: 17,000 98 battle tanks 14 aircraft 5 helicopters, including two Soviet-designed gunships 50 air defence guns 30 surface-to-air missiles Mortars and heavy artillery 112 armed vehicles, most in poor condition Shortage of basic supplies Estimates from International Institute for Strategic Studies

Macedonian troops have been using tanks, mortar and light artillery to shall positions held by the rebels near Gracani.

But the authorities have denied that Macedonian forces were responsible for the shellfire that fell inside Kosovo.

"The commander of operations in the Gracani area has said no Macedonian forces have used fire against targets inside Kosovo," said Defence Ministry spokesman Georgi Trendafilov.

A BBC correspondent who visited the area said up to 100 rebels of the National Liberation Army (NLA) have based themselves there, hidden in bunkers and shallow trenches.

Just a few days ago the Macedonian army was claiming significant progress in its efforts to drive out the NLA.

It had succeeded in pushing the rebels back from the hills around Tetovo, Macedonia's second largest city and the unofficial capital of its ethnic-Albanian community.

But so far their efforts around Gracani appear to have had little impact.

Nato steps up patrols

Nato forces along the Macedonia border are trying to cut off rebel supply routes.

Albanian rebels

Manpower: 300-700 Light anti-tank weapons Kalashnikov rifles Chinese-made machine guns Sniper rifles and mortars

Polish and Ukrainian troops already deployed in the area are being supplemented by some 400 British and Finnish troops equipped with sophisticated surveillance systems.

But the mountainous nature of the terrain in the border area which makes the task of both Macedonian troops and Nato peacekeepers difficult.

The BBC's defence correspondent, Jonathan Marcus, who is in Kosovo, says sealing the border with Macedonia is almost impossible.

The ethnic-Albanians are lightly armed and know the mountains well.