"I would expect that we should be able to sign the SAA (Stabilization and Association Agreement) with Bosnia-Herzegovina shortly, that is in April," he told AFP.

However Rehn underlined that the signing was conditional on Bosnia-Herzegovina adopting requisite laws concerning the police, "which they know very well."

The EU has made police reforms a key condition for Bosnia to seal an SAA accord, essentially a trade and aid pact which is the first step towards joining the rich European club.

Rehn and Bosnian officials put their initials to the pact in December, but the EU has refused to sign it until the police reforms are undertaken.

The leaders of Bosnia's Serb community insist on retaining control of police in their Republic of Srpska entity, which along with the Muslim-Croat Federation makes up post-war Bosnia.

But Croat and Muslim leaders want the forces to be unified and put under the authority of the state.

The head of the EU's police mission in Bosnia, Brigadier General Vincenzo Coppola, underlined Tuesday that three previous EU-driven attempts at obtaining the police reforms had failed.

The latest attempt, led by the ethnic communities themselves, is a "very minimal approach, but nevertheless it could be a step forward if they are willing to pass the laws." He told reporters in Brussels.

"If they don't produce something, there will be no signature of the SAA."

Rehn's remarks came with Bosnian leaders due in Brussels Tuesday and Wednesday to evaluate developments in Bosnia, and as the mandate of the EU and international representative there, Miroslav Lajčak, comes up for renewal.

The EU is still supervising inter-communal relations, which remain complicated 12 years after the Dayton accords that ended the 1992-1995 war there.

The recent declaration of independence by Kosovo has been met by a threat from the Bosnian Serbs to follow its example and break away - something the EU dearly wants to avoid.

More than 10,000 Bosnian Serbs protested in Banja Luka Tuesday against the move by Kosovo's ethnic Albanian leaders and demanded the right to secede themselves on the same grounds.

Hundreds of them clashed with police outside the U.S. consulate.

Lajčak is expected to see his term renewed again this week, but officials with close knowledge of the dossier suggest that a time limit may be put on his mandate for the first time, in line with a demand by Russia.