[Syrian refugees on a dinghy drift in the Aegean sea off the Greek island of Kos in Greece]The United Nations agency for refugees called on central European countries to overcome public opposition and give more help to refugees from war-torn regions. The UNHCR made its plea on Thursday, before a summit of the Visegrad group - Poland, Hungary, Czech Republic and Slovakia -opens in Prague on Monday. The group opposes European Union efforts to distribute asylum seekers across the EU and instead wants to emphasise securing the EU's external borders.