Bosnian Serb leader Milorad Dodik pushed on Tuesday for a referendum on the authority of Bosnia's national court over ethnic Serbs, stepping up a challenge to the country's integrity two decades after it emerged from war.
Dodik asked lawmakers in the autonomous Serb Republic to back the referendum, arguing the court was biased against Bosnian Serbs.
The proposed vote comes after Dodik's ruling SNSD party in April made it official party policy to push for a referendum on the Serb Republic's secession in 2018 unless the region is granted greater powers.
The latest initiative will deepen concern in the West that Bosnia risks unravelling 20 years after a 1992-95 war in which 100,000 people died.
The Serb Republic and a Federation of mainly Muslim Bosniaks and Catholic Croats make up post-war Bosnia, joined by a weak central government in a highly-decentralised and unwieldy system of ethnic quotas.
While the Bosniaks and Croats on the whole want greater integration with the West, Dodik has sought to strengthen ties with traditional Serbian ally Russia.
"The number of indictments and verdicts against the Serbs before the national court proves irrefutably a selective approach to justice, which aims to lay blame exclusively on the Serb people," Dodik told the Serb Republic parliament.
Foreign powers overseeing the peace in Bosnia issued a statement warning that the Serb Republic parliament may only call referenda "on issues falling within its competence".
Russia, however, which is also a member of the Peace Implementation Council alongside the United States, European Union and others, did not sign the statement.
Serbs in particular were angered last month after Switzerland decided to extradite Bosniak wartime commander Naser Oric to Bosnia, rather than Serbia, after he was arrested by Swiss police on a Serbian warrant for war crimes against Serbs.
Bosnia argued it was pursuing its own case against Oric, which Dodik says is a farce.