Jean Tiberi and Jacques Toubon would seem to have a lot in common. Both studied law, became Gaullists and faithfully served President Jacques Chirac for more than two decades. Their ambitious wives, Xaviere and Lise, always defended Jean and Jacques with sharp tongues and long fingernails.

But the strongest thing shared by Jean Tiberi, the 63-year-old Mayor of Paris, and Jacques Toubon (57), the former minister of justice, is intense personal loathing. That became apparent this month when Mr Toubon resigned as an adviser to President Chirac so he could attack Paris's massive 19th-century neo-Renaissance town hall.

On April 6th Mr Toubon took 32 city councillors, including 13 of Mr Tiberi's deputies, with him in his revolt against the mayor. The rebels formed their own political group and demanded Mr Tiberi's resignation.

Not only would Mr Tiberi never, never resign, he said: "I will personally see to it that Mr Toubon never becomes mayor of Paris." He said he was the victim of aggression, and called the renegades "putschists", a term last used when the generals in Algiers tried to overthrow Charles de Gaulle.

Mr Tiberi fired the 13 faithless deputy mayors who had sided with Mr Toubon. Their chauffeur-driven cars were taken from them, and the mayor sent cardboard boxes to their offices to help them pack. Mr Tiberi says he may replace the "putschists" next week, but he is not in a hurry. As a consequence, the city government is paralysed. Unless the cabinet takes the extreme measure of dissolving the Paris city council by decree, Mr Tiberi has another three years as Mayor of Paris. "If it goes on like this," he predicts, "in 2001 Paris will fall to the left."

In the meantime, the Cain and Abel of Gaullist politics trade daily insults. Mr Toubon's office has been broken into. Sadly, the newspaper Liberation wrote, the battle for Paris is not about ideology, strategy or ethics, "nothing but naked ambition, a cynical offensive and tribal divisions."

The two men's mutual hatred started in May 1995, when Jacques Chirac, who had been Mayor of Paris since 1977, became President of France. Messrs Tiberi and Toubon both wanted to succeed him at the town hall; Mr Chirac chose Tiberi for the mayor's job and gave Mr Toubon the justice ministry as a consolation prize.

Their rivalry deepened with the June 1997 legislative elections, when Mr Tiberi saved his seat in the National Assembly and Mr Toubon lost both his cabinet and parliamentary seats. Mr Toubon blamed his loss on Mr Tiberi, whose wife's misdeeds involved him in the much-publicised dispatch of a helicopter to the Himalayas to find a vacationing French judge to quash an investigation into payments to Xaviere.

The Tiberis are an embarrassment to the President's party, but the mayor's 30 years of service to Jacques Chirac make it impossible to fire him, or even take sides in the unseemly quarrel. "The President of the Republic does not intervene in local politics," a terse statement by the Elysee said.

Both Mr Tiberi and his wife Xaviere are the children of poor Corsicans, and the unkind word ploucs (country bumpkins) is often used to describe them. The couple have acquired five Paris apartments in the past two decades, but nonetheless lodged both their adult children in luxurious subsidised housing. Their son Dominique found his "low income housing" poorly decorated, so the City of Paris spent 1.5 million francs (£178,571) refurbishing the flat before he moved in.

Dominique Tiberi also benefited from an Air France salary, although he did not work for the airline. An investigating magistrate discovered that Xaviere Tiberi had received 200,000 francs (£23,809) for writing a 36page report on the use of French abroad, most of which was plagiarised. In both scandals, legal proceedings were dropped.

Then there was Mayor Tiberi's victory in last June's legislative election. (Many French politicians accumulate public offices, and it is not unusual to be both a mayor and member of parliament.) His opponent, the Socialist Lyne Cohen-Solal, accused Mr Tiberi of vote-rigging in his Paris 5th arrondissement district.

The case went to the Constitutional Council, which concluded that false residence certificates had been provided for pro-Tiberi voters. But the council did not invalidate Mr Tiberi's victory, on the grounds he would have won the seat anyway. Another investigation into illegal kick-backs at the city housing board, headed by Mr Tiberi, continues.

The battle for Paris is the third chapter in the disintegration of the French centre right, which began with President Chirac's dissolution of parliament a year ago. In chapter one, the right lost its parliamentary majority; in chapter two, its policy towards the extreme right-wing National Front fragmented in last month's regional elections. Now another bastion of the right's power, the city of Paris, has shattered.