The European Union (EU) has cancelled accession negotiations with Croatia planned for Friday due to a border dispute between Croatia and Slovenia, the Czech Republic, which holds the rotating EU presidency, said on Wednesday. 'Despite substantial efforts to facilitate a solution to the country's border dispute with Slovenia, Croatia's accession talks remain blocked and no new chapters can be formally opened or closed,' the Czech Republic said in a statement. 'The (EU) presidency deeply regrets the fact that despite numerous attempts by the presidency and the European Commission to help find a way forward, the negotiations have not progressed.' The border dispute remains a bilateral issue to be solved only by Slovenia and Croatia, it added. EU Enlargement Commissioner Olli Rehn was brokering a deal between Croatia and Slovenia, but failed to make any headway. Croatia and Slovenia have not been able to completely draw their land and sea borders since their independence from the former Yugoslavia in 1991. Slovenia, a member state of the European Union (EU) since 2004, partially blocked Croatia's previous round of accession negotiations with the EU in December. 