Treaty seals Europe's historic expansion to the east

Twenty-five European leaders hailed a "landmark in history" yesterday when they signed a treaty in Athens formalising the European Union's expansion eastward.

At a lavish ceremony in the shadow of the Acropolis, the leaders of the 15 existing EU members and 10 newcomers signed the document, which will enlarge the Union in May next year.The new states are Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia and Slovenia.

"With this step, the Union is finally overcoming the division of the European continent into east and west," Gerhard Schröder, the German Chancellor, declared. "Just like the Berlin Wall [in 1989], today is a reason for shared joy – joy that we are creating a united and peaceful Europe."

But Jacques Chirac, the French President, who stunned the acceding countries when he upbraided them earlier this year for supporting the US-led war on Iraq, again warned the new states to toe the line.

"This new Europe will not be able to fulfil our citizens' expectations if, as we are seeing in the current crisis, its political ambitions are not clarified and its running is not extensively rethought," he said.

"The European Union is about more than just a large market, common policies, a single currency and free movement," he said pointedly. "It is more importantly about a collective ambition, shared disciplines, firm solidarity and naturally looking to the European family."

The remarks were aimed at Poland, Hungary and the Czech Republic, which joined Britain, Spain, Italy, Denmark and Portugal in backing the US at the United Nations. Pro-American sentiment runs high in the former Iron Curtain countries and M. Chirac's comments foreshadow potential difficulties in the new EU. France and Germany have traditionally dictated the Union's political direction, and are only now coming to terms with the prospect of a shift in the power balance. Aleksander Kwasniewski, the Polish President, made his position clear yesterday, saying: "We want Europe to be based on wise transatlantic ties."

A succession of leaders described the impending enlargement as a landmark. "This Union represents our common determination to put an end to centuries of conflict and transcend former divisions on our continent," the leaders said in a joint statement.

It is not the end of the political process though, as formal accession will be confirmed only after a series of referendums. Hungary, Slovenia and Malta have all registered "yes" votes in recent weeks and the remaining countries will all have to ratify the treaty, except Cyprus.

The main contrast between the 10 countries joining the Union now, and the last enlargement, when Austria, Finland and Sweden joined, is in the relative size of their economies. The new wave includes Poland, which will become the fourth-largest member state in terms of population, but the acceding states only have a combined gross domestic product equivalent to that of the Netherlands.

Three more EU candidate countries – Bulgaria, Romania and Turkey – were present in Athens. The first two are expected to join in 2007 but Turkey's path is blocked, largely by Cyprus, where a peace plan for the divided island has failed.