So far, Croatia has provisionally closed seven policy chapters during its EU membership talks.
Three policy chapters ready for closing are being blocked by Slovenia, and the verification procedure is under way in the Council of the EU for benchmarks for another two chapters: Statistics and Freedom of Movement for Workers.
The sources said that Croatia could forward the benchmarks for closing an additional five chapters by the end of this month.
In this case, the number of closed policy chapters will be raised to 17.
According to the same sources, the negotiating process is going on despite Slovenia's blockade.
Croatian and EU negotiators are in permanent contact, and hundreds of documents are circulating between Zagreb and Brussels.
It is frustrating that the public cannot see the progress, but Croatian negotiators are working on remaining chapters, the sources said.
Sweden, which takes over the EU rotating presidency, has said that the membership negotiations with Croatia would be a priority of its chairmanship.
Sweden has announced the organisation of four intergovernmental conferences between Croatia and the EU or even more, if necessary, during its 6-month presidency over the Union, the same sources said.
Slovenia is currently blocking the opening of nine policy chapters.
In the event of the lifting of the blockade until the next intergovernmental conference, set for 26 June, Croatia could have 31 policy chapters opened. In that case, only two chapters will remain for opening: Judiciary and Fundamental Rights and Competition Policy.