The case has dragged on for more than two years, after the International Criminal Tribunal for the former Yugoslavia (ICTY) issued arrest warrants in January 2015 for three associates of radical Serb Vojislav Seselj.
Defence lawyers Petar Jojic and Vjerica Radeta, and former war-time associate, Jovo Ostojic were charged in December 2014 with "having threatened, intimidated, offered bribes to, or otherwise interfered with two witnesses," in two cases involving Seselj.
Ultranationalist Seselj was acquitted in his main trial in March 2016 of nine charges of war crimes and crimes against humanity arising from the 1990s Balkan conflicts.
But the three others are still wanted for trial on the separate charges, and the court based in The Hague has grown increasingly angered by Belgrade's refusal to hand them over.
Presiding judge Alphons Orie on Tuesday ordered court officials to "address Interpol seeking distribution of a red notice in relation to the accused on the basis of the arrest warrants."
He added it was clear "Serbia's continued non-compliance with its obligations obstructs the course of justice."
Interpol says on its website that red notices can give "high, international visibility to cases". Wanted persons are also flagged to border officials "making travel difficult."
The ICTY judges in 2012 handed Seselj a two-year jail term in the separate contempt case.
Seselj was allowed to travel back to Serbia in 2015 to undergo cancer treatment while awaiting the verdict in his main trial, which he did not attend.
Since then, Seselj has repeatedly lashed out at the UN tribunal, and his Radical Party was returned to parliament in Belgrade in April elections.
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