Serbian state security agents raided three homes of suspected helpers of fugitive top war crimes suspect Ratko Mladic, seeking leads to the former Bosnian Serb military commander, an official said on Thursday.

The raid was conducted on Wednesday, a day before chief UN war crimes prosecutor Serge Brammertz presents a report to the Security Council about Serbia's cooperation with his office.

The arrest of Mladic, indicted by the UN war crimes tribunal in The Hague for genocide over the 1995 Srebrenica massacre of 8,000 Muslims and the siege of Sarajevo, is seen as key for Serbia's bid to join the European Union.

"We did not strike on Wednesday because of (Brammertz's) report, but because of operational findings that prompted us to act," a state security official told Reuters, speaking on condition of anonymity.

In a draft of the report obtained by Reuters earlier this week, Brammertz said he was satisfied with Serbia's efforts but stopped short of using the yardstick term "full cooperation". EU foreign ministers are due to decide next Monday whether the improvement is sufficient to unlock a trade pact with Belgrade.

During the raid, agents found "notebooks, address books, several CDs, computer hard disks and cell phones," the source said. "Hopefully, we will gather some good evidence that might give us a solid lead to the man."

Over the past few months, agents have raided homes and offices of several people suspected of aiding Mladic.

Serbia must also arrest Goran Hadzic, the political leader of Serbs in Croatia during the 1991-95 war there.

Belgrade arrested former Bosnian Serb political leader Radovan Karadzic in 2008 and handed him over to the tribunal, hoping to secure the start of a pre-membership deal with the EU.

But the Netherlands, whose peacekeepers were deployed in and around Srebrenica during the 1995 massacre, insisted Mladic be captured before Serbia enjoys the trade benefits of the accord.

Rasim Ljajic, Serbia's Labour Minister, who is coordinating cooperation with the U.N. tribunal, said the authorities were searching on the assumption that Mladic is hiding in Serbia.

"It is clear that Mladic has helpers or he could not stay at large," said Ljajic, who has pledged to resign if Mladic is still at large after Dec. 31. "But their numbers are dwindling."

"We are not aiming strictly at them," he told Vecernje Novosti daily. "They are more like a tool to lead us to Mladic."

(REUTERS)