Former French President Valery Giscard d’Estaing

London, May 19: The EU treaty cannot be renegotiated if French voters reject it later this month, its architect has warned.

Valery Giscard d’Estaing, ex-French President, is fighting to persuade his own countrymen of accepting his draft constitution. Britain is looking to ditch its referendum planned for next year if the French and other countries reject it, Jack Straw, foreign secretary, signalled today.

The Netherlands are set to hold a referendum also.

The draft constitution sets out new rules to make the EU function more smoothly following its enlargement last year. It also caters for a permanent EU president and a stronger defence force.

A rejection by France could in theory torpedo the constitution. Today D’Estaing described renegotiation as “impossible”.

“There is absolutely no plan B,” he told BBC Radio 4’s Today programme.

The French statesman was speaking after a day of confusion at Westminster about the consequences for the government’s plans to hold a referendum here on the constitution in spring next year if France rejects the document in its poll on May 29.

Speaking in the House of Commons, Douglas Alexander, the new Europe minister, suggested Britain’s vote would go ahead come what may.

But shortly afterwards Straw appeared to put a question mark over that.

He told the BBC that all EU member states had signed up to a legal obligation to ratify the treaty ? in many cases by referendum. That obligation would continue unless the European Council revoked it.

The French opinion polls are saying the vote is too close to call.

Jacques Chirac, the French President, and Gerhard Schroeder, the German chancellor, appealed to French voters to say “yes” before talks between the two leaders began today in Nancy, France.

“France assumes a big responsibility, the responsibility not to let down us other Europeans over the constitution,” German Chancellor Gerhard Schroeder said.

German foreign minister Joschka Fischer said before the talks in Nancy that a French “No” would encourage other member states to follow suit in similar ballots.

Economists say defeat of the treaty could also send ripples through financial markets.

Meanwhile, Spain last night became the ninth country to ratify the constitution with an overwhelming vote in favour in its Senate for the landmark document.

All 25 EU members need to approve the constitution for it to take effect.