Poland takes over a six-month EU presidency on July 1 and Tusk, asked if he would be the person to sign the accession treaty with Croatia, said: "I would be very glad to, although that doesn't depend only on Poland's engagement but on the 100 per cent engagement of the Croatian government as well."

"I think Croatia is one of the countries deserving to complete the accession negotiations with the EU as soon as possible," Tusk said, adding, "When I addressed Croatian leaders in Gdansk six years ago, I said Croatia could always count on Poland's support, that we would unconditionally support Croatia's European aspirations."

Poland has designated progress in enlargement as a priority of its EU presidency, he said.

"That refers to Croatia as well as to other countries whose goal it is to join the EU. And it is my personal wish that those decisions be made during Poland's presidency. In particular because the countries that will chair the EU in the future could focus on other issues more than on enlargement," Tusk said, adding "we should therefore do the utmost so that this happens by the end of the year."