The Yugoslav Government has condemned the sacking of the ultra-nationalist Bosnian Serb President, Nikola Poplasen.

Correspondent Jacky Rowland: "Western intervention taken to a new level"

The ruling party of President Slobodan Milosevic described the sacking - ordered by the top international official in Bosnia, Carlos Westendorp - as a violation of the Dayton peace agreement.

"[It] is an illegal act, an act of unprecedented wilfulness, and the most serious violation of the letter and spirit of the Dayton and Paris accords, the Serb Republic constitution, and the Bosnia-Herzegovina constitution thus far," said a government statement broadcast on Serbian TV.

Mr Westendorp dismissed President Nikola Poplasen on Friday, accusing him of obstructing the peace process.

President Poplasen, a hardliner, had refused to appoint the caretaker Prime Minister, Milorad Dodik - a moderate who enjoys broad support from western officials - to the post permanently.

"President Nikola Poplasen has abused the authority of the office of the president of the republic, ignored the will of the people ... and consistently acted to trigger instability," Mr Westendorp's spokesman said.

Mr Westendorp's spokesman James Ferguson: "Enough is enough"

Mr Westendorp - a Spanish diplomat appointed by the international community to oversee the implementation of the Dayton peace agreement which ended the Bosnian war in 1995 - has powers to impose legislation and remove officials.

But President Poplasen said he would fight his dismissal by calling a referendum.

Later on Friday, an international panel of arbitrators declared the disputed town of Brcko - so far controlled by the Bosnian Serbs - a neutral district outside the jurisdiction of the Bosnian Serb Republic and the Moslem-Croat Federation.

Both the Serbs and the Muslims have been claiming the right to have the town officially declared as part of their territory.

Shortly after the Brcko ruling, Mr Dodik announced he was resigning as Prime Minister because of the decision.

Nato-led Bosnian peace force has been beefing up its presence in Brcko and a spokeswoman for the force urged its Serb population to remain calm.

The US Embassy urged Americans to keep away from Bosnia, particularly its Serb part.

Bosnian Serb shot dead

A US soldier with the Nato-led Stabilization Force (Sfor) shot dead a Bosnian Serb on Friday night outside a restaurant in the northeastern town of Ugljevik.

An Sfor spokesman said that the incident occurred after Sfor troops were attacked by a group of local men carrying wooden clubs.

Bosnian Serb sources named the man killed as Krsto Micic, Deputy Chairman of the Ugljevik Serb Radical Party.

Strained relations

A BBC correspondent in the region, Jacky Rowland, says the dismissal of the Bosnian Serb president is Mr Westendorp's most significant intervention in Bosnian politics.

Nikola Poplasen claims Mr Westendorp cannot fire him

So far he has used his powers against mayors and local police chiefs who have interfered with the return of refugees from other ethnic groups.

Relations between President Poplasen and Western officials have been strained for a while.

In February, the international Contact Group said it would support "strong action" by Mr Westendorp if Mr Poplasen continued to refuse to nominate a prime minister-designate able to secure a parliamentary majority.

Enforcing the peace process

Post-war Bosnia comprises a Serb republic and a Muslim-Croat federation, each with wide autonomy.

International officials and a Nato-led peace force are trying to ensure compliance with the Dayton agreement.

No party has a majority in the Bosnian Serb Parliament, where hardline nationalists sit alongside representatives of Muslims and Croats.

Western officials argue that the moderate Mr Dodik is the only politician capable of securing a parliamentary majority and of winning vital international aid for impoverished Bosnian Serb towns.

Our correspondent says the dismissal of Mr Poplasen highlights the lack of success of Western officials in making the peace process in Bosnia self-sustaining.