In an interview published on Friday by the Sarajevo-based Dnevni Avaz daily, Del Ponte said Mladic and Radovan Karadzic had to be in The Hague by the end of the year, but that her priority at the moment was Mladic's arrest, which she expected Serbian authorities to do.
Del Ponte said she would not exert pressure on Belgrade to arrest both men, but that she would insist on Mladic's arrest because she knew that he was within the reach of Serbian authorities.
She went on to say that there had been some indications that Mladic might surrender voluntarily, which resulted in optimistic statements about his imminent transfer to The Hague.
Now it seems that Mladic will not surrender, so an operation should be launched to locate and arrest him, she said.
She stressed that Belgrade no longer questioned her claims that Mladic was in Serbia and that he enjoyed the protection of the army.
There are still some problems in that regard, so the international community, in particular the European Union, should step up pressure by making the start of stabilisation and association talks with Serbia and Montenegro conditional on Mladic's extradition, she said.
Commenting on Karadzic, Del Ponte said that he was still in the area between eastern Bosnia and Montenegro and that his arrest required cooperation between local authorities and the European Union Force (EUFOR) and NATO.