German President Horst Koehler called on Saturday for reforms of the European Union to consolidate a form of "diversity and dialogue" 50 years after the founding of the bloc.

Hosting a dinner for leaders from other 26 EU countries, Koehler urged the bloc to raise its efficiency and competitiveness especially after the recent expansion.

European integration is an "irreversible trend," he said.

Meanwhile, Koehler called on the EU to have dialogues with other cultures so that the countries can "coexist in harmony" despite all the differences.

The European Union "is more than a union of economic purposes," he said.

According to the leaked draft of the Berlin Declaration to be adopted by the EU leaders on Sunday, the 27 EU nations have agreed to build a "renewed common ground" by 2009, even though the promise falls short of mentioning the word "constitution."

"The political forms of Europe must always be renewed according to the change of times," said the declaration.

The EU constitution, designed to streamline the bloc's regulations, is virtually dead after two of the EU founding fathers, France and the Netherlands, rejected the draft treaty in separate referendums in 2005.

German Chancellor Angela Merkel, expected to present a roadmap for the revival of the constitution by the end of Germany's EU presidency in June, had hoped for a strong push for the constitution during the informal EU summit in Berlin.

The ambitious plan has recently been played down due to the differences among the 27 EU members.