EU leaders rounded off the Laeken summit on Saturday evening with agreement on a new constitutional convention which will draw up plans to create a more democratic structure for the union.

In a declaration described as "far reaching", the leaders agreed to develop a new approach through the convention, which will be chaired by the former French president, Valery Giscard d'Estaing.

The Belgian prime minister, Guy Verhofstadt, said that there will be "no taboos" in the areas open for discussion.

Peter Mandelson is said to be on a shortlist of British representatives for the new body.

The leaders also agreed to plans for "big bang" expansion, ruled out the development of an EU superstate and called for a greater emphasis on issues such as climate change and crime.

However, the summit ended on a sour and "near-farcical" note after leaders failed to reach agreement on where new EU regulatory and executive agencies should be located.