Nato says the Kosovo Liberation Army is intensifying its attacks on the Yugoslav army.

Jonathan Charles: KLA is a useful tool for Nato

The alliance spokesman, Jamie Shea, said the guerrilla group was like "a phoenix rising from the ashes", and said it was gaining thousands of new recruits.

For three days this week, a camera crew filmed a unit of the KLA in action, providing a rare glimpse of life inside the disputed province.

The KLA is a symbol of hope for ethnic Albanians but it has also become an important tool for Nato.

On a hill deep inside Kosovo, the patrol gathers intelligence about troop movements. In the valley below a Serb armoured unit is dug in, hidden from Nato war planes.

Ammunition is running low

Near this tunnel the KLA claims there is an underground ammunition dump. The location will be passed to Nato, identified as a potential target.

For the patrol it is a perilous operation though, the Serbs fire back from positions just 500 metres away, hoping to frighten off the KLA unit.

Once safely away, the KLA use mobile phones to give the latest information to Nato contacts.

During their patrols, the KLA encounter the daily reality of ethnic cleansing. In a village a house is ablaze. Homes were burned down, the inhabitants forced out.

A senior officer, his identity disguised, told us the devastation only fuelled the anger of his men.

In the isolated village where it has set up headquarters, the KLA knows failure may consign ethnic Albanians to permanent exile.

More than 100 troops live here constandly training, and the size of the unit gives a lie to Serb claims that the KLA is wiped out. However, it is running short of ammunition.

Around the border where the KLA is active we saw a Serb armoured personnel carrier in the distance and smoke on the horizon, plenty of targets for both the KLA and Nato.