SARAJEVO: Russian Foreign Minister Sergey Lavrov said on Monday that any attempt to change the US-brokered Dayton peace agreement that ended Bosnia's war 25 years ago may have "grave consequences".

Lavrov was speaking on a visit to Bosnia on the anniversary of the day when the peace accords, agreed previously in the US air base in Ohio, were signed in Paris by the then presidents of Bosnia, Serbia and Croatia, all parties to the Balkan wars of the 1990s.

"We are witnessing the efforts to bring down the Dayton, to erode it ... this may cause risks and grave consequences," Lavrov told a news conference in East Sarajevo.

He said the deal must not be changed in any way, referring to comments by some Western diplomats and Bosnian politicians that the agreement, which was made to stop the war, needs to be upgraded to enable Bosnia to make progress forward with reforms.

The peace deal ended the war among Bosnian Serbs, Croats and Bosniaks (Bosnian Muslims) in which about 100,000 people were killed and two million were moved from their homes.

But a quarter of century later Bosnia, which was split into two autonomous regions, remains dysfunctional, with reforms blocked by the rival ethnic leaders. The two regions are the Serb-dominated Serb Republic, and the Federation shared by Bosniaks and Croats, all linked via a weak central government.

Upon his arrival, Lavrov first visited Milorad Dodik, the Serb member of the country's three-man presidency, in the Serb Republic's government office just outside the capital Sarajevo.

He urged the closure of the office of an international peace overseer in Bosnia which was set up as part of the Dayton deal, saying that international protectors should have left the country "long ago".

Dodik has repeatedly said that any changes to the Dayton structure would be the reason for the Serb Republic to secede from Bosnia.Lavrov is scheduled to separately meet the leader of the largest Croat HDZ party on Monday evening.