The meeting, organised by the think tank Friends of Europe, the Konrad Adenauer Foundation, the Stability Pact and the Constantinos Karamanlis Institute for Democracy, focused on economic development as a key to achieving stability.
Rehn said that each candidate for EU membership had to meet all the accession criteria and that candidate status did not automatically guarantee a safe entry. He added that the Balkans faced a long road, with some countries being years away from joining the bloc.
Croatian Foreign Minister Kolinda Grabar-Kitarovic said that the magnetism of EU membership was a factor of stability.
By combining its favourable geographical position and adjusting its legislation to that of the EU, Croatia had become "a credible partner and a factor of stability" in the region, she said.
Montenegrin Prime Minister Milo Djukanovic said that all Western Balkan countries had recognised the strength of regional cooperation, but complained that the level of foreign investment was still too low due to outstanding political processes.
Recalling that next year Montenegro would hold a referendum on independence from Serbia, Djukanovic welcomed ongoing efforts by the international community to settle the status of Kosovo, adding that once the issue was settled Serbia would have the opportunity to fully focus on its European agenda and become a factor of stability in the Balkans.
Croatian National Bank Deputy Governor Boris Vujcic said that trade between Balkan countries was "more than appropriate", but that the volume of trade with the EU was too low.
Doris Pack, a member of the European Parliament, said that the region's greatest problem was a high unemployment rate, which reached as much as 70 per cent in Kosovo and was directly responsible for a high crime rate.
Also attending were Serbian President Boris Tadic, Kosovo Assembly member Bajram Rexhepi, former Italian Prime Minister Giuliano Amato, and the director of Microsoft Southeast Europe, Goran Radman of Croatia.