This is a moment of truth and we should do our utmost to solve the issue before the European Council's meeting on Thursday and Friday, Rehn said in Luxembourg on Monday morning just before his talks with the EU presidential troika consisting of France, the Czech Presidency and Sweden, on a standstill in Croatia's EU membership talks caused by the Slovenia-Croatian border row.
Czech Foreign Minister Jan Kohout expressed optimism about the outcome of Rehn's efforts before the troika's meeting with the commissioner.
Upon his arrival in Luxembourg this morning, Slovenia's Foreign Minister Samuel Zbogar said that he expected Rehn to bring to the table some new ideas for the resolution of the border row and the resumption of Croatia's EU entry talks.
The latest compromise proposal by Rehn was fully accepted by Croatia in May with Croatian officials saying that the proposal was presented as a take it or leave offer.
The Slovenian side, however, forwarded amendments to it, which Zagreb finds to be unacceptable.
Slovenia insists on being allowed to have direct access to international waters in the northern Adriatic sea which it shares with Croatia and Italy.
There are also disputable points at the land border regarding some hamlets in Istria.
Slovenia accuses Croatia of prejudging the outcome of the border demarcation in documents it forwarded to Brussels within the negotiations on policy chapters. Therefore Ljubljana has been blocking the opening and closing of some policy chapters within Croatia's EU membership talks for several months.