Mr Kaczynski added that the new treaty should "reflect the EU's real needs. And the European reality is a reality of states, mostly national states."

The statement comes just days before several EU leaders and intellectuals gather in Salzburg to attend a high-profile conference called "The Sound of Europe" hosted by the Austrian presidency.

Their debate should focus on the future of the union and it should add up to the "reflection period" launched by the EU leaders last year, following the rejection of the EU constitution in France and the Netherlands.

Vienna is expected to analyse the year-long discussion on what to do with the failed constitutional project in June, but it is still far from clear which direction the bloc's leaders will take to resolve the issue.

The European Parliament has recently approved a report calling on key EU players to salvage the existing charter, possibly with some additional texts to face concerns expressed by the French and Dutch.

But according to the Polish president, the current constitution is too much forward-looking, as it refers to an as yet unformed single European identity.

"Today, the European identity manifests itself in opposition to something, for example opposition to the United States, and building a common identity on such a basis of antagonisms is the worst path for a united Europe," he said.

Mr Kaczynski was elected last year along with his identical twin Jaroslaw, the leader of the ruling Law and Justice party, both of them popular for their mild euroscepticism and for their support of traditional Roman Catholic values.