“My role is to see, at an operational level, if everything possible is done in order to be successful,” Serge Brammertz, the chief UN war crimes prosecutor, told reporters.

“While recognizing that a number of people are really doing an excellent job, we say at the same time that there is room for improvement and in a number of areas, there can be done more, and in a more professional way.”

Serbia’s past inability or unwillingness to find Mladic has long delayed its progress toward the European Union, deterring foreign investment and diminishing EU accession funds.

A UN war crimes court has indicted Mladic for genocide in the 1995 massacre of 8,000 Muslims in the Bosnian town of Srebrenica and the 1992-95 siege of Sarajevo.

In October, EU foreign ministers asked the bloc’s executive commission to consider starting entry talks with Serbia, but warned Belgrade any further progress will depend on its full cooperation with the UN war crimes tribunal.

Brammertz said he would send on Wednesday his latest six-month report on Serbia’s efforts to apprehend Mladic to the UN where the Security Council will discuss it on Dec. 6.

On his latest regular visit to assess progress in dealing with war crimes committed during the 1992-95 Balkan wars, the prosecutor said that he had asked Serbia earlier this year to devote more resources to the search, review their strategy and take a more multi-disciplinary approach.

One key to finding Mladic, who led ethnic Serb military forces during the 1990s Bosnian war, is his support network.

“He is of course a professional. He has worked long enough in professional services to know how to hide and how to take countermeasures toward investigative approaches,” Brammertz told reporters. “It is obvious that he is not alone, and it is obvious that he has the support of other persons.”

The Mladic issue is the most prominent factor that has left Serbia lagging behind many other former Yugoslav republics.

Slovenia is already an EU member; Croatia is close to becoming a member; both Macedonia and Montenegro are further along in the process than Belgrade. Even Albania, the region’s most isolated state under Communism, is ahead of Belgrade.

Only Bosnia and Kosovo, which remain international protectorates, trail Serbia in progress toward EU membership.

Investigators believe Mladic is likely to be hiding in or around Belgrade, perhaps in one of the drab Communist-era apartment blocks in the capital’s New Belgrade section of town.

“The main working hypothesis is that the solution to his arrest is in Belgrade, but of course operational activities are concentrated not only on Serbia but are logically also into other areas,” Brammertz said.

Serbian officials say Mladic hid in army barracks until 2002 under the protection of military and state security hard-liners before going underground. An trial of his past helpers has uncovered evidence he was in Belgrade until at least 2006.