Reuters said on Wednesday that a low rank monitoring mission would visit Croatia next week.
The source said that neither the Luxembourg presidency nor European institutions in Brussels had any information that a mission was expected to visit Zagreb next week.
Following the postponement of Croatia's European Union entry negotiations last month, the Union set up a task force to evaluate Croatia's cooperation with the UN court. The task force will convene for the first time in Luxembourg on April 26 for a ministerial meeting.
The task force comprises foreign ministers Jean Asselborn of Luxembourg, Jack Straw of Great Britain, and Ursula Plassnik of Austria, EU foreign and security policy high representative Javier Solana, and enlargement commissioner Olli Rehn.
The task force will then hold separate meetings with chief prosecutor Carla del Ponte and Croatian Foreign Minister Kolinda Grabar-Kitarovic.
The task force will draw up a report on Croatia's cooperation with the Hague tribunal based on information from the Croatian government, the tribunal's Office of the Prosecutor, and probably other sources.
It is unknown how many times the task force will convene before drawing up the report or if an EU delegation will visit Zagreb after April 26, although this has not been ruled out.
Luxembourg's minister for Europe, Nicolas Schmit, has said recently that the task force will hold talks before drawing up a report, for the first time on April 26, and that a visit to Zagreb is possible so the report could be finished.
According to sources from Luxembourg's EU presidency, the task force might finish the report by May 20, when the Union's foreign ministers will hold their regular monthly meeting.
A number of European officials have recently said that in writing the report, a lot of weight will be given to del Ponte's opinion. Solana has said there is no doubt that the most important data and assessments will come from the tribunal, and that everyone must cooperate with the UN-founded court.
EU leaders decided at a summit in December that entry negotiations would be launched with Croatia on March 17 provided that Zagreb cooperated fully with the tribunal. The negotiations were postponed after EU foreign ministers on March 16 failed to agree as to the fulfilment of that commitment.
The key role in the postponement was played by del Ponte, whose report said that Croatia had not done its utmost to locate and hand over General Ante Gotovina, and that he was within the authorities' reach.
Today, Croatian newspapers said that Gotovina fled Croatia in 2001 with a fake passport. The Interior Ministry has launched an investigation into these allegations.