The names in the highly-sensitive report have not been made public.
Last week, a former security chief to Mladic was arrested on suspicion of having helped him evade justice.
The tribunal’s chief prosecutor Carla Del Ponte has demanded Mladic’s arrest by the end of the month, so that he can be tried in The Hague alongside other senior military and police officials in relation to the Srebrenica massacre.
She has called for the European Union to suspend its negotiations with Serbia over closer cooperation, in order to pressurise Belgrade into handing Mladic over.
Del Ponte is due in Belgrade on February 6 for further talks with the authorities over cooperation with the tribunal.