Rehn said he was briefed about the latest report which the ICTY submitted to the UN Security Council.
"Some progress has been made but for the time being cooperation cannot be described as full," Rehn said in a statement, referring to a report by the UN tribunal's chief prosecutor Carla del Ponte.
The EU Enlargement Commissioner Rehn said he regretted that del Ponte could not describe the cooperation as full. According to Reuters which cited diplomatic sources the chief prosecutor's verdict made it almost certain the European Union would not open entry talks with Zagreb before the end of June under the Luxembourg presidency.
Rehn said Croatia needed more time for democratic structures to gain full control over the state. "I understand that the Croatian authorities need more time to ensure that democratic structures are fully in control and that the entire state administration complies with the rule of law and with international obligations," he said.
Del Ponte sent a copy of her report to the Luxembourg Presidency of the EU on Tuesday evening. She will send the report to the UN Security Council on June 13, together with a letter stating similar assessments. According to European diplomatic sources, del Ponte said cooperation at this moment was not full, but that progress had been made. She said if Croatia continued to implement the action plan, cooperation could be full in several months. Del Ponte said she remained concerned that Gotovina was still not located and transferred.
The Luxembourg Presidency has forwarded del Ponte's report to all EU member countries.
Croatia was scheduled to start its EU entry talks on 17 March, but they were postponed because the EU member states could not agree that Zagreb entirely cooperated with the tribunal in The Hague. The EU then set up a five-member task force in charge of assessing Croatia's cooperation with the tribunal.
At its first meeting in late April, the task force decided they would meet again in case Carla del Ponte changed her assessment.