The units of the Rapid Reaction Force, based in central Bosnia, were expected to arrive on Mount Igman last night where they will take up their positions overlooking Sarajevo.
The deployment, described by a UN spokesman as a "turning point" for the UN mission, followed Western assurances made on Friday at the London conference that Serbian aggression would no longer be tolerated. Early yesterday, Serb forces attacked a UN food convoy and base resulting in two French soldiers being killed and three wounded. President Jacques Chirac said his troops would not cave in to Serb military pressure in Bosnia and would strike back if attacked in Sarajevo. "The Serbs had better understand that we won't give in," Mr Chirac warned. "I want to say right away that the instructions given are to reinforce our positions around Sarajevo with the Rapid Reaction Force and shoot back systematically ... if we are attacked again."
The Mount Igman reinforcements comprised at least 320 British soldiers, a company of French light tanks and French engineers. The British contingent includes two batteries of the 19th Field Regiment of Royal Artillery with twelve 105mm light guns with a range of over 10 miles. The soldiers were clearly glad to be doing something tangible. "The UN's been losing face. It's time to stop pussying about," one said.
From the south-western slopes of the mountain, shielded from the Bosnian Serb fire which rakes the final bends of the treacherous mountain road - the city's only lifeline - the guns will be able to strike back at Serb artillery and mortars.
One infantry company of the Devon and Dorset Regiment with 16 Warrior armoured fighting vehicles was also on its way. "Their mission is to respond to attacks against Sarajevo," said a UN spokesman, Lt-Col Chris Vernon. An armoured column of some 500 French Foreign Legionnaires left their base at Tomislavgrad in western Bosnia to reinforce UN peace-keepers in Sarajevo.
The chorus of threats against the Serbs was joined by President Bill Clinton, who said US air power should be used in Bosnia if Serb aggression continued, especially against the Gorazde "safe area", but reiterated that US ground troops would not be sent into combat.
"I do believe we should use American air power if the Serbian aggression continues to erode the commitments that they have all made, for example, to respect the integrity of Gorazde," Mr Clinton said.
Despite the West's tough stance, however, heavy fighting was reported across Bosnia yesterday. The Bosnian Serbs renewed their assault on the eastern "safe area" of Zepa and joined with Croatian Serbs and a rebel Muslim militia in an attack on the Bihac area in the north-west. Some 2,000 people are fleeing the onslaught.
Croatia, which borders on the Bihac enclave and is waging a new campaign to recapture territory it lost to rebel Serbs in 1991, promised military aid to Bosnian government troops in Bihac on Saturday, setting the scene for an escalation of the conflict in both former Yugoslav republics.
Commenting on reinforcements for Sarajevo, the Defence Secretary Michael Portillo said: "There is no shift in any sense from peacekeeping to war fighting. We simply wish to provide protection to peace-keepers who are trying to save lives in Bosnia ... If we could have a secure overland route, that would be the best guarantee on the survival of Sarajevo and its people."
An opinion poll showed that British public opinion has swung in favour of much tougher action by the West in stopping the carnage by the Bosnian Serbs among the Muslims. The poll, carried out by Mori on Friday as the international conference reached a decision on action to take against the Bosnian Serbs, showed a majority of 52 per cent supported a decisive shift from peace-keeping towards British troops becoming involved in the conflict.
It also found that half those polled were ready to risk the lives of British soldiers in Bosnia to protect the Muslim population, and 59 per cent supported the use of British forces in air attacks on the Bosnian Serbs.