President Sarkozy toasted a landmark victory last night as the French Parliament narrowly backed his overhaul of the country's 50-year-old Constitution in a Bill that will curtail some of his power. The reform, described by his supporters as a significant modernisation of French democracy, was approved by only one vote after arm-twisting by the centre-right Government to win over MPs and Senators.

With the left-wing opposition expressing resolute hostility and a three-fifths majority necessary to change the Constitution, the President had feared his most humiliating defeat since entering office last year. Far from relinquishing power, critics accused Mr Sarkozy of using the reforms to cement his authority.

The Senate and the National Assembly met for a joint session at the former French Royal Palace in Versailles, where King Louis XVI summoned lawmakers in 1789 in an attempt to curtail the popular discontent that eventually cost him his head.

Mr Sarkozy secured a more successful outcome after interrupting a three-day break with Carla Bruni, his pop star wife, in the Moroccan city of Marrakesh to charm - or berate - parliamentarians over the telephone. He needed 538 votes and obtained 539.

The flagship legislation to revise 47 of the 89 articles in the Constitution, and to add nine new ones, was touted as a way to bring French autocratic structures into line with other Western democracies. Reformers said that it would end the semi-monarchic presidency tailor-made for General Charles de Gaulle, the French war-time hero, under the 1958 Fifth Republic Constitution.

Mr Sarkozy hoped that by abandoning some levers of power he would also deflect attacks from opponents who said that he had turned the executive into a one-man show with ministers reduced to bit-parts.

The bill restricts the President's tenure in office - currently unlimited - to two five-year terms, and it strengthens the powers of a weak parliament. MPs will be able to veto some presidential appointments, control half of their agenda and vote on military interventions lasting more than four months. The reform also opens the way for a “people's referendum”.

In a move designed as an obstacle to Turkey, treaties to approve new members of the European Union will also be submitted for a referendum unless they win a three-fifths majority in Parliament.

Mr Sarkozy said that the measures would turn France into an exemplary democracy. His supporters said that many of the changes had been mooted by the Socialist Party, which was opposing them only in the hope of giving Mr Sarkozy a bloody nose.

The Left accused him of buttressing the presidency and some right-wing MPs said that he would undermine it.

Attacks focused on a clause that would enable the President to deliver a State-of-the-Union style address to Parliament. Socialists said that the rest of the package was window-dressing to divert attention from this measure, which will give Mr Sarkozy a stage denied to French heads of state since 1873. They said that it signalled the demise of the job of the Prime Minister, which has traditionally consisted of putting presidential directives into practice. Mr Sarkozy is in effect to become the chairman and chief executive of France, they said.

“Contrary to what Nicolas Sarkozy claims, we are headed straight for a reinforced system of monocracy,” Robert Badinter, the Socialist Senator, said.

Critics were concerned by the way the Government threw money and pledges at wavering centre-right MPs. Writing in La Montagne, the regional daily, columnist Xavier Panon said that many legislators had been promised “subsidies, promotions, ministerial posts and remunerated missions”. One MP was told that his constituency would be abolished if he failed to toe the party line, it was claimed.

Jacques Myard, a diehard Gaullist, remained opposed to the reform. He said: “Limiting the President to two terms is stupid because if you know he will step down in his tenth year in office nobody will take any notice of him from his eighth or ninth year in office. You are weakening the President's power.”

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