Nanterre, France ? In a blow to President Jacques Chirac and his conservative government, a court Friday convicted a key ally and potential successor, former Prime Minister Alain Juppe, in a party financing scandal and barred him from office.

Pale and close to tears, Juppe rushed out of the packed courtroom by a back door, his illustrious political career in tatters, after the three-judge panel found him guilty of overseeing the systematic use of public funds to pay workers in Chirac’s party.

The court in the Paris suburb of Nanterre sentenced Juppe, 58, to a suspended 18-month prison term for “illegally taking advantages.”

Its sternly worded verdict — more severe than the eight-month suspended sentence sought by the prosecution — could doom any hope for Juppe, once one of France’s brightest political stars, of ever ascending to the presidency.

“While vested with an elected public mandate, Alain Juppe betrayed the trust of the sovereign people,” the ruling said. “The nature of the acts committed is intolerable to society.”

Under French election law, the conviction automatically barred the legislator and mayor of Bordeaux from voting for five years and holding office for 10.

Juppe’s lawyer, Francis Szpiner, said he would appeal.

He attacked the judges’ ruling as “questionable and unjust” and suggested it was politically motivated. “The court wanted to throw Mr. Juppe out of politics,” Szpiner said.

The punishment will not take effect until a higher court rules on the appeal, which could take a year.

The judges’ decision could herald legal problems for Chirac once the president leaves office, because in convicting Juppe, the court condemned a system of political financing in place in the 1990s when Chirac was Paris’ mayor.

Former Prime Minister Alain Juppe, center, arrives with his lawyer Francis Szpiner, left, at the Nanterre hall of justice, outside Paris. Juppe was found guilty Friday in a party financing scandal and declared ineligible for public office for 10 years.