Three people suspected of helping war crimes fugitive Ratko Mladic avoid capture were arrested yesterday.
The three were arraigned before an investigative judge, said a Belgrade district court spokeswoman.
The arrests come a day after the European Union froze aid and trade talks with Belgrade for its failure to detain the ex-Bosnian Serb army commander.
Also yesterday, the government issued a pledge to step up its efforts to arrest Mladic, indicted for genocide in Europe's worst massacre since World War II.
"All our services have been given orders to quadruple their efforts to find this needle in the haystack," said Cabinet minister Predrag Bubalo.
Carla Del Ponte, chief prosecutor at the tribunal in The Hague, Netherlands, said this week that Serbian authorities knew Mladic's location as recently as 10 days ago and could have arrested him before he disappeared again.
Mladic is wanted by the UN war crimes tribunal for the former Yugoslavia, charged in the 1995 slaughter of 8,000 Muslim men and boys in the Bosnian enclave of Srebrenica. He is thought to be getting protection from hard-liners in the army and his Serb wartime allies.
Mladic commanded Bosnian Serb forces during the 1991-95 Bosnian war in which an estimated 200,000 people were killed and millions forced from their homes during fighting notorious for brutal "ethnic cleansing" campaigns.