Proposals by Valéry Giscard d'Estaing, the former French president, who is supervising a new constitution for the European Union, are likely to raise concern that countries will have to choose between leaving the EU and signing up to a more integrationist agenda.

Mr Giscard d'Estaing is set to ask his Convention on the future of Europe to consider allowing EU treaties to be approved even if some countries fail to ratify them.

Proposals he puts forward on Thursday will also give countries wishing to leave the EU two years to agree the terms of their departure. These proposals have been endorsed by the Convention's governing praesidium but have yet to be discussed by all 105 members.

"We need to realise that what just about works with 15 countries cannot work with 25," said Inigo Méndez de Vigo, one of the praesidium members. "You don't want an agreement that can be kidnapped by two or three small islands."

Ten mainly small countries, including Malta and Cyprus, are scheduled to join the EU next year, creating a situation in which smaller and medium-size states vastly outnumber bigger countries.

"Clearly the 'exit clause' and the question of how treaties should be ratified are intimately connected," said a European Commission official.

But some people close to Mr Giscard d'Estaing say that treaty changes which transfer sovereignty to the EU, rather than just deciding how to use powers it already has, should always be decided by unanimity.

Mr Giscard d'Estaing maintains that if any country fails to ratify the constitution, the European council of EU leaders should meet to resolve the "political problem". People close to him say the Convention could only establish rules for the ratification of subsequent treaties.

Approving the new constitution could be especially fraught, since several countries, such as France, Italy and Spain, have indicated they would hold referendums to decide on the subject. In a 1992 French referendum on the Maastricht treaty, just 51.05 per cent voted in favour.

This week, seven of the EU's smaller members, including the Netherlands, Belgium and Ireland, held a summit in Luxembourg to warn against Mr Giscard d'Estaing's idea of a full-time president of the European council of EU leaders.

The "exit clause" for countries wishing to leave the EU is also controversial, and was opposed by some praesidium members who feared it would hand eurosceptics a tool to stir up anti-EU sentiment.

But the praesidium as a whole backed a draft article that would make a country's departure effective two years after it made its decision to leave, unless a different agreement had been reached with the rest of the European Union.

Mr Giscard d'Estaing believes it is unrealistic to expect all member states to agree on the terms of a country's exit, and considers two-thirds of countries - or possibly a "qualified majority" - should be enough to sign up to a deal.

Financial Times, April 2 2003