Karadzic mobilises Serbs into work units: Serbia's President finds war no longer works to his advantage - His allies in Bosnia begin to hand back seized weapons

THE BOSNIAN Serbs, apparently chastened by a Nato air strike against one of their guns on Friday night and the threat of more to follow, yesterday returned to UN control five heavy weapons they had seized on Friday. But they also moved towards a full state of war after the imposition of an embargo by their patron, Serbia.

General Sir Michael Rose, UN force commander in Bosnia, called in Nato jets after Serb soldiers stole a tank, two armoured personnel carriers and an anti-aircraft gun from a UN depot inside the 20km heavy weapons exclusion zone imposed by Nato around Sarajevo. A second anti-aircraft gun was taken from the same weapons depot later the same day.

In Pale, the Bosnian Serb 'capital', Radovan Karadzic, the self-styled President, ordered the immediate mobilisation of a compulsory workforce to gather the harvest, prepare refugee accommodation and repair economic infrastructure. Mr Karadzic told local authorities to 'refresh and re-organise the compulsory work units in detachments and brigades', adding that all people of working age 'must be subject to the compulsory work, regardless of their religion and nationality, ie on the basis of equality and without any form of discrimination'.

His order means that Serbs must join Muslims and Croats forced to labour on behalf of the self-styled 'Srpska Republic' in Bosnia.

Despite their political isolation, enforced by Serbia's decision to close its border with Bosnia, the politicians in Pale show no sign of accepting the international peace plan and thus helping to end an embargo on Serbia. The Speaker of the Bosnian Serb parliament in Pale, Momcilo Krajisnik, yesterday said he expected deputies to 'declare a state of war, general mobilisation and rationing of supplies'. The Bosnian government army has had some success recently on several fronts, taking ground along the northern Posavina corridor and Vares, north of Sarajevo.

Despite obeying yesterday's UN orders, the Serbs continued to deploy snipers in Sarajevo. The UN announced plans to send anti-sniping patrols along both sides of the line, and peace-keepers on the Bosnian side fired at the Serb snipers several times. Several explosions, probably due to rifle grenades, reverberated around the city. A UN spokesman, Major Rob Annink, said the Serbs fired three mortars - banned from the exclusion zone around the city - on Friday morning.

Major Annink warned the Serbs that the threat of Nato retribution will remain until they return or remove five or six other heavy weapons - and possibly 20 or more - now at large in the exclusion zone, in violation of the Western ultimatum called in February to end the shelling of the city.

'There is an ultimatum,' Major Annink said. 'This is just a pause (in the Nato action) and we may well continue.' However, it seems unlikely the UN will call the jets in again, as General Rose is keen to return troops to their peace-keeping mission.

The dramatic scenes enacted over the past few days have brought Bosnia back into the international limelight; the Serbian hawk has transmogrified into a dove, the peaceable UN has sent in its war planes and the local villains have been punished. But the Bosnian Serbs seem, if anything, to be preparing for a bloody climax.

In Belgrade, opposition politicians (that is, genuine rather than nominal opposition leaders) have urged the Serbian people to unite around President Slobodan Milosevic to avert the threat of a Bosnian Serb takeover led by General Ratko Mladic.

However, the idea that General Mladic, or his political counterpart, Mr Karadzic, could out-manouevre the wily Mr Milosevic seems unlikely.

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