The UK government on Monday announced an assets freeze on a marketing agency that helped organise a controversial "national day" for Bosnian Serbs, despite it being deemed anti-constitutional.
Europe minister Leo Docherty said the agency, Mania, had "rightly tarnished" its reputation by profiting from the "illegal" and divisive event marking the unilateral declaration of a Bosnian-Serb republic in 1992.
Republika Srpska (RS) is one of two entities of Bosnia and Herzegovina established by a peace deal which brought hostilities to an end in November 1995 following the Bosnian war.
One half of the country belongs to the Serb entity RS while the other is ruled by a Muslim-Croat federation
The sanction means Mania, which is based in Banja Luka, is now subject to an assets freeze and cannot do business with UK companies.
"Our action today should serve as a warning to others, whether politicians or businesses, who seek to destabilise the country," said Docherty.
"The UK will continue to support and protect peace and stability in Bosnia and Herzegovina and the wider Western Balkans region."
"Republika Srpska Day" was marked on January 9 as a public holiday and saw some 3,000 people march in a parade in Banja Luka, the RS administrative centre.
Bosnian Serb President Milorad Dodik attended the event with other RS officials and Russia's ambassador to Bosnia.
The UK said Dodik and other figures had previously used the event "as a vehicle to promote secessionist rhetoric in violation of the country's constitution, to deny the Srebrenica genocide and glorify war criminals convicted of crimes against humanity".
Meanwhile, the agency said it was "shocked" by the move.
During its nearly decade-long existence Mania has worked on projects for partners that included the European Union, some United Nations' agencies "but also projects with the UK embassy" in Bosnia, an agency statement said.
Regarding the organisation of the RS "holiday" the agency said it had "adhered to the norms and rules of the profession and professionally fulfilled the obligations."
It said its employees would "without unnecessary politicisation ... continue to prove their creativity and quality in the realisation of domestic and foreign projects, through professional engagement".
London in April 2022 sanctioned Dodik and senior politician Zeljka Cvijanovic "for their attempts to undermine the legitimacy and functionality" of Bosnia and Herzegovina.
Ministers at the time said the pair had been "encouraged" by the example of Russian President Vladimir Putin.
