Serbia's deputy prime minister resigned on Wednesday over the government's failure to arrest war crimes suspect Ratko Mladic and the resulting suspension of EU pre-membership talks with Serbia.

The government "betrayed the most important interest of the country and citizens of Serbia" by failing to arrest Mladic and so secure the conditions for talks with the European Union, Miroljub Labus said in his resignation letter to Prime Minister Vojislav Kostunica.

Labus is also Serbia's chief negotiator with the EU.

The European Union announced Wednesday it had suspended pre-membership talks with Serbia-Montenegro in response to Belgrade's failure to deliver the wartime Bosnian Serb army commander to the U.N. war crimes tribunal in The Hague, Netherlands, by an April 30 deadline.

"As a vice premier and the chief of the negotiating team for joining the EU, I do not want to be part of the policy" of failed promises toward The Hague tribunal, Labus said, adding he remained "deeply convinced that there is no better way of life than the life in the European community."

Labus stressed that his departure may not necessarily lead to the collapse of the Cabinet. His liberal party, G17 Plus, which holds three posts in Kostunica 20-member Cabinet, plans an internal vote Saturday on whether to quit the government, he said.

Even if the party decides to walk out, its deputies in Serbia's parliament will continue to support the minority Cabinet "as long as Kosovo talks continue," Labus said, referring to crucial international negotiations concerning Serbia's breakaway southern province.

But Rasim Ljajic, Belgrade's chief liaison with the U.N. war crimes court, predicted "political turbulence" ahead, as the Cabinet would "reap negative points" for the EU's decision.

"This could seriously shake the government," Ljajic told AP Television News. "But I don't think the nation should plunge into despair. Instead, we must pull up and intensify our efforts to bring Mladic to The Hague."

At least two opposition party Wednesday demanded the immediate resignation of the entire Cabinet, including Kostunica.

One of them, the Liberal-Democrats, said Kostunica and all his ministers "bear the responsibility" for Serbia being shut out by the EU.

Labus also criticized the republic's security services — known to be staffed by hard-line nationalists and Mladic's supporters — and said they had "searched for Mladic everywhere except where he was hiding."

"They did not do their job properly," Labus said.

However, Kostunica defended his team, maintaining that the government had "done absolutely everything in its power" to capture Mladic and send him to The Hague.

With the recent arrests of several alleged Mladic aides, Kostunica said the fugitive's "entire network has been uncovered" and that "Mladic is now hiding all alone."

The prime minister also called on Mladic to give himself up.