BELGRADE - Serbia warned on Thursday it would defend Serb rights in Bosnia against Western-inspired threats with as much determination as it is applying to prevent the Western-inspired secession of its own Kosovo province.

"Preserving Kosovo and Republika Srpska are now the most important goals of our state and national policy," Prime Minister Vojislav Kostunica said, in a statement for the first time overtly linking two potential, ethnically based crises.

Pledging support to Serb kin in Bosnia, who had Belgrade's full backing in the 1992-95 Bosnia war under ultranationalist strongman Slobodan Milosevic, Kostunica said there was now "an open threat to the essential interests of the Serb people."

Kostunica said he told Bosnian Serb Prime Minister Milorad Dodik he could count on Serbia's full support in a dispute which flared at the weekend, over an edict changing the rules of law-making in Bosnia's complex post-war system of government.

A Bosnian Muslim leader accused Kostunica of fuelling a crisis in Bosnia as leverage in Serbia's Russian-backed campaign to stop Kosovo Albanians declaring independence after December 10 if negotiations on the province end with no deal, as most expect.

Bosnia's Muslim community together with Bosnian Croats make up half the country, sharing power with its Serb half in an unstable, uneasy and now tottering partnership.

TWO-WAY SECESSION CRISES?

"Vojislav Kostunica's statements today represent a flagrant interference in internal matters of Bosnia-Herzegovina," said Haris Silajdzic, Muslim member of Bosnia's three-man presidency.

"Their clear goal is the simultaneous culmination of crises in Bosnia-Herzegovina and Kosovo at the moment when the Kosovo issue is being decided" in a bid to "maximize (Serbia's) position in negotiations on Kosovo" Silajdzic said.

Past threats by the Bosnian Serbs to secede from Bosnia if the Albanian majority in Kosovo wins independence prompted strong warnings from Bosnia's international peace overseer that any move to dismantle the dual state would be stopped.

Linking the future of Kosovo and Bosnia raises the specter of radical changes of border and forced population shifts in the Balkans, eight years after the West went to war over Kosovo to stop the last ethnic conflict in the break-up of Yugoslavia.

But on Thursday, the ultranationalist Socialist Party of the late Milosevic went further than Kostunica, saying Serbia "should recognize the independence of the Bosnian Serb Republic" if Kosovo becomes independent with Western recognition.

Dodik on Monday threatened to quit Bosnia's fragile central government unless the current overseer, Miroslav Lajcak, rescinds an order reducing the quorum required to pass laws -- a step he says he took to stop obstructionist absenteeism.

The Serbs of Bosnia are determined to defend their extensive autonomy against Western-backed efforts to forge a more unified state than the duopoly created at the end of the war by the flawed Dayton Peace Accords.

Kostunica said he agreed with Dodik that the edict was a threat to Dayton, which set up the two-part state, in the same way a U.N. envoy's plan for an independent Kosovo would violate U.N. Resolution 1244, confirming Serbia's legal sovereignty.

Bosnia's international peace overseer Miroslav Lajcak said he did not know what prompted Kostunica, schooled in international law, to make such a statement. But he "knows as a legalist that what he is stating is not true."

"I dismiss most resolutely every artificial linkage of the Dayton peace agreement and the Resolution 1244," Lajcak said.

Kostunica said Lajcak's measures were aimed at "abolishing Republika Srpska" -- the policy advocated by Silajdzic in the interests of forging a unitary state Serbs vow never to permit.

(Additional reporting by Daria Sito-Sucic)