Leaders of 11 southeastern European countries, including Bulgaria, attended the opening of the Southeast European Cooperation Process (SEECP) in Istanbul on June 23, in which they penned a joint declaration condemning the recent Israeli raid on the aid flotilla headed to Gaza."We deplore the loss of life and injuries during the incident in international waters," said the declaration.The countries say they want "an impartial, independent and internationally credible investigation on this matter." They stress the urgent need to address the humanitarian situation in Gaza, saying they expect announcements from Israel on easing the blockade of Gaza to be quickly followed by "concrete measures" with immediate positive impact on the lives of the people of Gaza.Turkish president Abdullah Gul presided over the summit. Other heads of state in attendance include Albanian president Bamir Topi, Croatian president Ivo Josipovic, Bulgarian president Georgi Purvanov and Montenegro president Filip Vujanovic.At the meeting in Istanbul, Serbia's president Boris Tadic also called on the European Union to openly tell his country "without making any excuses" whether it wants Serbia to join the 27-nation bloc or not.Tadic said at the opening of the Balkan summit that Belgrade does not want to be "used as a pretext to do absolutely nothing". Tadic's criticism comes despite assurances by the EU earlier this month that the door remains open to Balkan countries if they meet its criteria for joining.Four countries in the group - Bulgaria, Greece, Romania, and Slovenia - are already EU members, while Croatia and Turkey are in the process of accession talks. The group's other members are Albania, Bosnia-Herzegovina, FYROM, Moldova, Montenegro, and Serbia.The SEECP, which is designed to build stability and foster co-operation in the region, was launched upon Bulgaria's initiative in 1996.