Defiant troops remain on Mount Igman: Christopher Bellamy examines the military situation on the hills above Bosnia's capital

MORE THAN 1,000 Serbian troops yesterday remained on Mount Igman, the ridge which overlooks Sarajevo airport and the beleaguered city beyond. Just 150 French UN troops fanned out across the commanding height, still vulnerable hostages in the event of Nato air attacks against the Serbs, and set up radar. The UN Protection Force spokesman in Sarajevo, Commander Barry Frewer, said the United Nations was not present in enough strength to do anything more than monitor the situation.

The United Nations is having a hard time following Serbian movements on the forested slopes - which hardly bodes well for precision air attacks if the Serbs do not comply with UN demands. But the UN said there was movement towards opening potential aid routes north to Visoko and south-west towards Hadzici. The details are to be discussed in the mixed military working group, comprising the three factions and chaired by the UN commander in Bosnia, Lieutenant-General Francis Briquemont.

UN sources said yesterday the Muslim-led Bosnian army had withdrawn north-east from the Igman ridge down to Hrasnica, by the airport, while the Serbs were withdrawing east towards the road running south-east to Foca. Serbian movement was reported around Babindol and the junction to the north. Some of the Serbian troops known to have left the area have been seen further east, in Pale, the Bosnian Serb 'capital'. Sources said a 'substantial' force - about two Serbian 'brigades', of perhaps 500 men each - remained on the wooded ridge.

Following Muslim-Serb fighting on Mt Bjelasnica two days ago, the Serbs withdrew, damaging one of the television towers on Bjelasnica. On Thursday, French UN forces began repairing the road to Tarcin - the main Mostar road, which is badly damaged.

In the present delicate and confused situation, air attacks on the Serbs look unlikely. Nato air attacks would be directed by Forward Air Controllers (FACs) with the UN forces. There are several ways of directing aircraft against ground targets, one of which is to 'lase' - designating the target with a laser beam.

The FACs are UN troops, wearing blue helmets, although so far they are all from Nato countries, and are trained in a set of Nato procedures. The FAC teams normally move as part of the UN units on the ground.

The Army yesterday dismissed reports that members of the Special Air Service Regiment might designate targets for the attacking aircraft as 'pure speculation'. While FAC teams have specialist skills, that does not mean they are 'special forces'.

If the UN requests action by Nato aircraft, Nato pilots must ensure their own Rules of Engagement are satisfied - that there is little danger to friendly forces or to civilians - before launching the attack. There are thus two sets of Rules of Engagement - one for the 'customer', the UN, one for the 'supplier' of air strikes, Nato.

In Sarajevo, Commander Frewer said four platoons of UN peace-keeping troops (about 150 men) were fanning out on Mt Igman and nearby Mt Bjelasnica, whence the Bosnian Serb army is withdrawing. The Bosnian Serbs say they have taken all their soldiers off Igman; Commander Frewer said the Serbs still had sizeable forces on the mountain, which curves round Sarajevo to the south-west. 'We are probably talking in the thousands,' he said.

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