United Nations officials in Zagreb were anxiously monitoring the mobilisation of tens of thousands of Croatian army troops and rebel Serb forces last night, possibly in preparation for full-scale war.
In Bosnia, meanwhile, UN peace-keepers began to withdraw from the fallen "safe area" of Zepa, despite fears that several hundred civilians may still be hiding from the Bosnian Serbs in the steep, thickly wooded hills above the shattered town.
"We now assess there are as many as 100,000 Croatian soldiers fully mobilised and battle-ready and as many as 50,000 on the (Krajina) Serb side," Chris Gunness, a UN spokesman in Zagreb said. However, British intelligence sources place the total number of Croat troops at no more than 70,000.
Croatian Serb jets bombed Croatian army positions for the second day, as the Bosnian war seemed about to spill over into a new struggle for control of Serb-held terrirory in Croatia. Both sides send delegates to Geneva for peace talks today but little progress is expected.
The United States cautioned Croatia yesterday to exercise restraint, but, in effect, welcomed military moves by Zagreb which could relieve military pressure on the Bosnian government. In London, the shadow Foreign Secretary, Robin Cook, warned that Western governments were playing a "dangerous game", if they were encouraging Croatia to launch the new campaign to avert the need for military action by Nato. There was a danger, he said, of igniting a wider Balkan war.
However, appeals by both the rebel Bosnian and Krajina Serbs for help from the powerful forces controlled by Serbia proper appeared to have been rebuffed for the time being. President Slobodan Milosevic of Serbia yesterday sent nearly identical letters to Bosnian Muslim and Bosnian Serb leaders, appealing for an end to the war that he helped to begin.
"It needs more courage and strength to bring about peace than to start a war," he wrote to the Bosnian President Alija Izetbegovic. In a snub to Radovan Karadzic, the Bosnian Serb leader, he addressed a similar call directly to General Mladic, the military leader of the Bosnian Serbs and now his favoured client in Bosnia.
Zagreb wants the minority Serbs in the Krajina region, who broke away in 1991, to accept Croatian rule with guarantees of local autonomy. But the Krajina Serbs seem unlikely to accept Croatian President Franjo Tudjman's ultimatum that within 24 hours of the talks they must reopen rail links and oil pipelines running through their territory.
The decision to withdraw 200 UN troops from Zepa followed a demand from Paris that 78 French soldiers leave the conquered Muslim enclave by tomorrow morning. Two civilian officials will remain in the area for the next few days.
The UN had reinforced the "safe area" with French and Russian troops to supervise the forced evacuation from Zepa of civilians by the Bosnian Serbs. About 5,000 Muslims were taken in buses to government-held territory last week, but around 3,000 more, including up to 1,500 armed men, are thought to be hiding in the hills, fearful of Serb reprisals.
Hundreds of Zepa's former inhabitants have escaped across the border to Serbia, but the UN has reports that 200 men may have been detained by the Bosnian Serbs and that 600 may be trekking through Serb territory in the hope of reaching government-held central Bosnia.
Alexander Ivanko, the UN spokesman in Sarajevo, refused to speculate about French motives for the withdrawal, but another UN official said: "They just don't feel like having too many potential hostages."
General Mladic's soldiers are still exacting their revenge on Zepa. "The Bosnian Serb army is continuing to pillage in the villages," Mr Ivanko said. "Our officers on the ground have seen them loading cattle on to trucks and driving them out of the enclave."
A spokesman for the UN High Commissioner for Refugees said that a delegate had visited 60 refugees from Zepa who had reached the Serbian town of Mitrovica, across the Drina river.
"He interviewed 10 people, all of them men between the ages of 35 and 40, looking like civilians," Mans Nyberg said. "They looked very, very tired, extremely exhausted. They did not say anything other than that they had been walking for five days to reach Yugoslavia, and that they did not want to cross Bosnian Serb territory, fearing they would be killed," he continued.
"The Serbian authorities are very proud of these refugees and the media in Belgrade are making a big noise about them."