Serbia warned today that people helping war crimes suspects escape justice would also face prosecution.
Western pressure on Serbia is intensifying to show it is making serious steps to deliver top war crimes fugitives Ratko Mladic and Radovan Karadzic to the UN tribunal or have its paths to the European Union and NATO halted.
"I would like to warn all those who in any way communicate with war crimes fugitives indicted by The Hague, directly, in writing, by e-mail or carrier pigeons, they will be criminally prosecuted," war crimes prosecutor Vladimir Vukcevic said.
"We are all aware of the importance of the moment, the importance of cooperation with the Hague tribunal, it is one of the most important state jobs now," he told reporters.
He said authorities knew of several people who were in contact with the fugitives but declined to give details other than to say there were "certainly more than five of them" and to warn them they were risking prosecution.
Six UN war crimes indictees are still at large, all of them Serbians or Bosnian Serbs, including Karadzic and Mladic.
The wartime Bosnian Serb leader and his military commander have been charged with genocide for the 1995 Srebrenica massacre of 8,000 Muslims and the siege of Sarajevo, which claimed more than 10,000 lives during the 1992-95 war in Bosnia.
The screws were tightened on Serbia and Bosnian Serbs to hand them over after the arrest this month of Croatia's top fugitive, Ante Gotovina, in Spain.
In her annual report to the United Nations this month, UN war crimes prosecutor Carla del Ponte criticised Belgrade for failing to bring the two top fugitives to justice and accused parts of Serbia and Montenegro's army of blocking cooperation.
The EU has made it clear it could suspend at any moment talks on an association and stabilisation agreement started with Belgrade in October if it deemed cooperation with the tribunal was lacking.
Serbia delivered 13 war crimes suspects to the tribunal in the past year but the last suspect was handed over in April and a number of Western officials have told Serbia they wanted to see some action and no more promises.