Bulgaria is already a member of NATO and is due to join the European Union on January 1.
"I have come to Croatia with only one question: How can we help you?", Passy told reporters after meeting the chairman of the Croatian Parliament's Foreign Policy Committee, Gordan Jandrokovic.
Bulgaria considers it its duty to provide assistance to countries that wish to join NATO and the EU, just as Bulgaria was helped by its neighbours and friends, Passy said. "As of January 1, 2007 you will have yet another friend in the European Union," he added.
Passy said Croatia had made significant progress since 2004 when he last visited the country in his former capacity as head of the Organisation for Security and Cooperation in Europe.
"This progress should also be noted by the international community so that the two great Croatian projects could be brought to a successful close," he said.
Jandrokovic thanked Bulgaria for its support to Croatia and congratulated it on its forthcoming accession to the European Union.
Jandrokovic said that parliamentary cooperation between the two countries was very good, with no outstanding issues. "Bulgaria and Croatia can together play an important role in the region," he said.