The US embassy in Sarajevo has described claims by the Bosnian Serb leader that his security services are eavesdropping on the American ambassador there as “blustering”.

It also said his separatist policies are “gambling” with the future of the Serb entity in the Balkan state.

Milorad Dodik, a member of Bosnia’s tripartite presidency, claimed at a pre-election rally on Wednesday that the Bosnian Serb spying agency is now capable of listening to the conversations by US ambassador Michael Murphy and his staff.

“We also listening in on to them now, it’s not only them listening in on us,” Mr Dodik told his supporters.

“I know what they are talking about.”

He said this was not possible to do this just a few years ago.

“What we say in private is the same as what we say in public – the United States remains committed to Bosnia and Herzegovina’s sovereignty, territorial integrity, and multiethnic character and we will respond to any destabilising, anti-Dayton activity,” the US embassy tweeted, referring to a 1995 peace deal reached in Dayton, Ohio, between Bosniaks, Serbs and Croats that ended a war that left at least 100,000 people dead and millions homeless.

Although the peace deal ended the bloodshed, it left Bosnia deeply divided between the Bosniak-Croat federation and the Serb entity called Republika Srpska.

Mr Dodik has openly been striving to split the Serb entity from Bosnia and join it with neighbouring Serbia.

“All of Mr Dodik’s blustering cannot change the fundamental fact that the RS is not a state. It is one of BiH’s two entities,” the embassy tweet said.

“His pursuit of an ‘Independent Srpska in BIH’ isn’t protecting the RS or its residents, it is gambling with their future.”

Mr Dodik, known for his staunchly pro-Russian stance, has been under US financial and travel sanctions since January after President Joe Biden’s administration accused him of “corrupt activities” that threaten to destabilise the region.

Media in Bosnia say Mr Dodik is among politicians in more than two dozen countries who since 2014 were paid by Russia in exchange for exerting pro-Kremlin influence.

According to a newly declassified review by US intelligence agencies, Russia has spent at least 300 million US dollars (£261.2 million) to sway both politics and policy in those states.

There are fears in the West that Russia is — through the Bosnian Serbs and its Balkan ally Serbia — working on destabilising Bosnia to shift at least part of world attention from its war on Ukraine.