A new Western plan to revive Bosnia's stalled reforms so that it can sign a key accord with the European Union gives away too much to the Bosnian Serbs, Bosnian Muslim parties say.

After the 1992-95 war, Bosnia was split into two autonomous regions, the Muslim-Croat federation and the Serb Republic.

Bosnia's international peace overseer, Miroslav Lajcak, invited Muslim, Croat and Serb party leaders this week to discuss a new approach to a merger of Bosnia's two police forces, a key step towards reconciliation in the divided nation.

Details of the plan have not been made public and negotiations have not started, but Bosnian Muslim leaders already dismiss it as a capitulation to Bosnian Serb defiance.

"This is a devaluation of European priciples, we could not accept it," Sulejman Tihic, leader of one of the main Bosnian Muslim parties, told reporters on Thursday.

Ethnic Croat parties have been silent. The Bosnian Serbs first refused comment, then said the plan was unacceptable.

"His initiative does not back our stance on the police reform and does not represent a compromise solution," Serb Republic Prime Minister Milorad Dodik told a news conference.

"It is unconstitutional," he said without elaborating.

The EU has long pushed for the merger of the two ethnically based police forces, and made it a condition for signing a key pre-membership accord.

The Bosnian Serbs, widely seen as the aggressors in the war, have threatened to have a secession referendum if too many powers are taken away from them.

RESTRUCTURED, NOT UNIFIED

For the Muslims, Tihic said the new proposal did not provide for a unified police force but restructured the existing forces. Lajcak had "legitimised the existing police structure" by keeping the Serb Republic police, he said.

"It seems those who make radical statements and attack the international community are more appreciated," he added.

Lajcak took up the powerful post of overseer in July, pledging to speed up Bosnia's progress towards the EU and clinch the police reform deal in September.

One analyst said he had compromised too much in his drive to move the reform process forward.

"Police reform is one of Bosnia's key problems, it reflects the general political situation based on the conflict of two viewpoints from the war," analyst Senad Slatina told Reuters.

"The bottom line is which one will prevail -- the one born in wartime Sarajevo or that which promotes the ideas of (Bosnian Serb wartime leader and genocide suspect) Radovan Karadzic."

"There is no easy way out and Lajcak should have confronted this issue directly," he added.

Lajcak said he was "deeply disappointed" with the Muslim leaders' attitude because it showed "disdain for their colleagues and the political process."

"Furthermore, they rejected a proposal that is fair and balanced," he said in a statement

The EU joined the debate, reminding Bosnians of the importance of a deal. "Without an agreement ... the EU is unable to conclude a Stabilisation and Association Agreement," Enlargement Commissioner Olli Rehn said in a statement.

Lajcak's spokesman Eldar Subasic said on Friday negotiations would continue.