Russian-trained mercenaries are helping to establish a paramilitary unit serving the Serb separatist leader in Bosnia, it was reported in Sarajevo on Friday.

The report on the Žurnal news site, which was confirmed by the Bosnian security minister, comes at a time of mounting western anxiety about Russian efforts to destabilise the Balkans and resist Nato enlargement in the region.

On Tuesday, Milorad Dodik, the hardline leader of the Serb half of Bosnia, staged a military parade in Banja Luka in defiance of a ruling by the country’s constitutional court.

The Žurnal report said that a militia called “Serbian Honour” – which it said had been trained in a Russian-funded “humanitarian centre” in Serbia – was in the process of setting up a paramilitary group to be used against Dodik’s opponents.

It published photographs of the militia on the streets of Banja Luka, the administrative centre of the Republika Srpska, a semi-autonomous entity within Bosnia created by the Dayton peace agreement that ended the 1992-95 war. The pictures show the paramilitaries posing in black sweaters and in combat gear.

The report, including a picture of the award ceremony, says one of the group’s leaders, Bojan Stojković, is a former Serbian paratrooper who had trained in Moscow, and had been awarded a medal by Valeriy Kalyakin, a Russian general.

Dragan Mektić, the Bosnian security minister, said intelligence and security services were aware of the presence and activities of the group.

Zurnal said the group was recruiting from the Serb criminal underworld.

Zurnal said the group was recruiting from the Serb criminal underworld. Photograph: Zurnal

“We have been using this information for a long time, we have collected quite a lot of information about that,” Mektić said, adding he could not provide further details as his officials were compiling a full report for the Bosnian prosecutor’s office.

The Zurnal report said the group was recruiting from the Serb criminal underworld to form a new paramilitary unit loyal to Dodik. It quotes a leaked security service document as saying that Dodik’s aides discussed the aims of the new unit with “Serbian Honour” leaders and the goals would include “possible intervention if the opposition seeks to obstruct the functioning of the authorities”.

“For such a president, it is worth to give one’s life”, Stojković wrote under a picture of Vladimir Putin on his Instagram profile, according to the report.

Under the photo of Dodik, he wrote: “Nobody can do us any harm, we are stronger than destiny”.

The appearance of the paramilitaries in Bosnia comes 15 months after Russian intelligence was implicated in an abortive coup in Montenegro, in which mercenaries planned to storm parliament, assassinate Milo Đukanović, the country’s pro-western leader, , and prevent it from joining Nato. The plot was foiled and Montenegro became a Nato member in June 2017.

The Bosnian government is also pursuing Nato membership, but the resistance of the Republika Srpska under Dodik is hindering progress.

“This is part of a larger change in the international order, starting with the invasion in Georgia, Syria, Ukraine, the meddling in the US elections,” said Reuf Bajrović, Bosnia’s former energy minister, calling the appearance of the paramilitaries in Banja Luka a “watershed moment”.

“The Russians have decided to use their leverage in the Balkans to get the outcome they want: the end of the Dayton accords and the creation of a Serb statelet.”