Croatia's president Ivo Josipovic, right, and his Serbian counterpart Boris Tadić pay their respects to 18 Serbs killed by Croats in 1991, in the village of Paulin Dvor, eastern Croatia, November 4 2010.
European Enlargement Commissioner Stefan Füle has welcomed the "important step forward towards reconciliation" represented by the visits by Croatian president Ivo Josipovic and Boris Tadić to Vukovar and Paulin Dvor, sites of atrocities during the 1990s war in the former Yugoslavia.
"Such places could become the symbols of reconciliation and an example for the entire Western Balkans region," Füle said.
During a visit to a memorial to 260 people murdered at Vukovar, Tadić expressed his "apology and regret" the BBC said.
Vukovar was captured in November 1991 after a three-month siege by the Serb-led Yugoslav army. The victims of the massacre had sought refuge in the town's hospital. But two days after Vukovar was seized, they were led to the site of a pig farm and shot, their bodies left in a mass grave.
Tadić and Josipovic went together to the memorial at Ovcara and laid wreaths at the site of the mass grave.
Serbia recently made progress in its aspirations to join the European Union when the bloc’s foreign ministers agreed to forward Belgrade’s application to the European Commission.
At the same time, Serbia has been urged by the EU to meet key requirements including showing that it is co-operating properly with the international tribunal in The Hague on war crimes in the former Yugoslavia.
Serbia also has been told to show that it is building good neighbourly relations in the region, including with Kosovo, the independence of which is recognised by all but five of the EU’s 27 states but which is rejected by Belgrade.
Füle said: "We attach particular importance to good neighbourly relations and regional co-operation as part of the Stabilisation and Association process.
"Much has been done over the past year by the leadership in Serbia and Croatia, including the signing of several important bilateral agreements on police co-operation, defence co-operation and extradition of citizens suspected or convicted of serious crimes. We expect this commendable work to continue."
The fresh impetus that has been given to Croatia-Serbia bilateral relations by such high-level events could help to solve the outstanding bilateral issues in a true European spirit, Füle said.
"Both Croatia's and Serbia's future lie in the European Union, a Union where reconciliation is one of the founding features," he said.
Serbia news website B92 said that "an almost unanimous assessment of Serbian president Boris Tadić’s first visit to Vukovar is that it is a new page in history of Belgrade and Zagreb.
"However, what comes next is solving of specific problems, such as exchange of war documents and solving the issue of the missing persons, analysts say," B92 said.