A senior U.S. official warned Serbia-Montenegro (search) that it must extradite top suspects to the U.N. war crimes tribunal or jeopardize closer ties with Western Europe.

Serbia's new, pro-Western government, elected late last month, has promised to push for extraditions of several suspects, and the international community has set cooperation with the U.N. tribunal in The Hague, Netherlands, as a key condition for financial and political aid from abroad.

"We want Serbia-Montenegro to succeed and continue on the path of Euro-Atlantic integrations," Undersecretary of State Marc Grossman said.

"But there is a substantial obstacle on that road," he added. "It's time for that obstacle to be moved away ... It's a matter of meeting the obligations to The Hague tribunal."

Key suspects include Ratko Mladic (search), the Bosnian Serb wartime commander, and four Serb generals charged for their role in the Kosovo war.

"It's not something you should do to please the United States or the Europeans, it's something you should do because it's right for the Serbian people, it's an obligation you hold for yourselves," Grossman said.

Belgrade launched extradition procedures last week for the four generals, handing their indictments to a district court. But the process is stalled and it remains unclear when the handover will take place.

"It's time for Mr. Mladic to be in The Hague, it's time for the four generals to be in The Hague and it's time for justice to be done," Grossman said.

Mladic was indicted by the U.N. tribunal for genocide and crimes against humanity for ordering the 1995 massacre of thousands of Muslim boys and men in Srebrenica. He was charged together with another top suspect, Bosnian Serb wartime leader Radovan Karadzic (search).

Mladic has been a fugitive for nine years and is believed to be hiding somewhere in Serbia, though Belgrade denies it. Mladic's arrest and extradition have become key conditions for international support for Serbia-Montenegro and its desire to join the European Union and NATO.

Grossman indicated the United States would support domestic prosecution of some Serbs indicted by the U.N. court, including the four generals, who were indicted last year for atrocities committed during the 1998-99 Kosovo war. But that can only occur if Mladic is extradited first.

Vuk Draskovic (search), the Serbia-Montenegro foreign minister, said he agreed with Grosssman.

"Our obligations toward The Hague court are something that must not be bargained with, they must be followed through," Draskovic said. "We don't want to be an isolated island in the sea of European democracies."

"All the excuses have been long spent," Draskovic said.