PARIS (Reuters) - Serbia accused international mediators on Wednesday of trying to impose a fraudulent peace on Kosovo as the United States reported a big Yugoslav military buildup around the province. Serbian President Milan Milutinovic, arriving for a third day of renewed peace talks in Paris, told reporters the Yugoslav delegation had made viable proposals for Kosovo‘s institutions but "the others would like to have just a fraud." The U.S. Defence Department accused the Yugoslav military of moving more than 30,000 Serbian troops into and near Kosovo and "bracing for war" with NATO as the peace talks continue. Yugoslav forces maintained a relentless advance on ethnic Albanian rebel positions on Tuesday, pushing forward on two fronts in the centre of Kosovo and leaving villages ablaze. The three mediators— U.S. envoy Chris Hill, Russia‘s Boris Mayorsky and Austrian Wolfgang Petritsch of the European Union — rejected Belgrade‘s list of amendments to the draft autonomy accord negotiated in Rambouillet, near Paris, last month and accepted on Monday by the Kosovo Albanians. As for an alleged massacre of ethnic Albanians in January which triggered the latest drive to solve the year-old conflict, Finnish forensic scientist Helena Ranta said on Wednesday the deaths of 40 Albanians in the Kosovo village of Racak were a "crime against humanity". "This is a crime against humanity, yes," Ranta, appointed by the international community to conduct autopsies on the bodies, told a news conference in Kosovo‘s regional capital Pristina. But she declined to lay blame for the killings or use the word "massacre", saying such terms were outside her remit. The mediators have called a news conference for 6 p.m. (1700 GMT) on Wednesday, suggesting they will give the Serbs just one more day to start negotiating on the key implementation issues of a local police and a NATO-led peacekeeping unit for Kosovo. Diplomats said the co-chairmen of the talks, French Foreign Minister Hubert Vedrine and British Foreign Secretary Robin Cook, might return to pull the plug on this round of talks on Thursday if there was no progress. It would then be up to NATO to reactivate its plans for air strikes against Yugoslavia if President Slobodan Milosevic did not agree to accept foreign troops to implement an accord. But the chief Kosovo delegate at the peace talks, KLA political director Hashim Thaqi, said in an interview with the Kosovapress news agency: "Serbia is interested in continuing the war and we have to defend ourselves." In an apparent contradiction of the Rambouillet accord, which says the KLA must be demilitarised and disarmed, Thaqi was quoted as saying: "The KLA has its own military police. This police would be transformed, but the KLA would retain its status as the armed forces of Kosovo, as a defence force of Kosovo."