It is the EU's duty to launch association talks with Serbia and Montenegro, but this requires serious cooperation with the Hague tribunal, Solana said, adding that lack of progress in the cooperation would mean slower progress in the conclusion of a Stabilisation and Association Agreement with the EU.
Solana was speaking to reporters after meeting Serbia and Montenegro President Svetozar Marovic in Belgrade on Monday.
He also said he expected talks on the status of Kosovo and on Montenegro's future to be conducted in good faith and to produce results that would satisfy all the sides.
Marovic said that any ideas that might stop the progress of Serbia and Montenegro or set it on a backward course must not win in Kosovo. He added that he had conveyed his country's position that Kosovo needed realistic solutions, such that would not mean that only one side has won.
Solana said he was pleased to hear from Marovic that in implementing a referendum on Montenegro's independence all the parties concerned would respect recommendations from the Venice Commission.
During the day-long visit to Belgrade, Solana talked to the highest officials of Serbia and Montenegro.