(adds quotes from Serb official, para 13-14) By Ellie Tzortzi BELGRADE, Oct 26 (Reuters) - Serbia has the political will to arrest war crimes fugitive Ratko Mladic but some state officials are stalling, the chief United Nations war crimes prosecutor said on Friday. Carla del Ponte's assessment of how seriously Serbia is trying to arrest the former Bosnian Serb Army commander and three other suspects is key to Serbia's progress towards European Union membership. In Belgrade to meet top officials before preparing a progress report for Brussels, Del Ponte said she sensed that "a will to fully cooperate with (her) office exists". "I know that there are members of government and senior officials who are working very hard to track down these war criminals," Del Ponte told a meeting of NATO parliamentarians. "I also know that there are those who could do much more." She added that "if the declared commitment is turned into more effective leadership" and "more concrete actions are undertaken" she would be able to tell Brussels that there was progress in Serbia's cooperation with her Hague-based court. Mladic and his political boss Radovan Karadzic are indicted for the July 1995 Srebrenica massacre of 8,000 Muslims. Two other ethnic Serbs, Goran Hadzic and Stojan Zupljanin, are wanted for crimes committed in Croatia and Bosnia respectively. Serbia delivered two fugitives this summer after more than a year of inaction and defiance. The arrests unlocked frozen talks with the European Union on closer ties although Brussels said it wants more arrests before concluding negotiations. Last week the EU postponed a decision to initial the Stabilisation and Association Agreement (SAA) -- the first step to membership -- because Del Ponte said Belgrade's cooperation with her court was insufficient. In her speech, Del Ponte said there could be "no true peace" in the Balkans "until Mladic and Karadzic are in the dock". The fugitives are regarded as heroes by nationalists. "We still count on the European Union... to insist on Serbia's full cooperation with the Tribunal as a condition in the pre-accession and accession process," she said. "The Stabilisation and Association Agreement process between the EU and Serbia should only be finalised when Ratko Mladic is located or arrested." Serbia, along with Bosnia, is last in the queue of Balkan EU hopefuls. Fellow ex-Yugoslav republic Slovenia is already an EU member, Croatia is negotiating membership, Macedonia is an official candidate and Montenegro clinched an SAA last week. Even Albania, which spent some 45 years in isolation under a Stalinist regime, has signed the accord. Rasim Ljajic, Serbia's point man for cooperation with the Hague court, said it was "fully discouraging" for Belgrade that "the tribunal still conditions Serbia... and prolongs again the initialling of the SAA". The remaining arrests were now just a technical issue, independent radio B92 quoted Ljajic as saying, and "after 41 indictees sent to The Hague, there is no reason not to believe the rest would be extradited, if possible".
