Foreign Minister Eduard Kuka accepts the European Union's demand that fugitive indictee Ante Gotovina must be handed over to the Hague war crimes tribunal.
"There can be no yielding in that," he said, adding it was not absolutely certain that Croatia was not cooperating with the UN court.
Kukan maintains that opening entry talks with Croatia would send a positive signal to the Balkans. He said this was Slovakia's position.
The start of the negotiations is questionable given that the Hague tribunal's chief prosecutor, Carla del Ponte, recently accused Croatia of having failed to arrest Gotovina and said the government was not doing enough.
The final decision on the start of the talks is expected next week.