The former minister and speaker of France's National Assembly, Henri Emmanuelli, has died at the age of 71, reports Radio France Internationale.
A longstanding figure on the leftwing of the ruling Socialist Party, he supported Benoît Hamon in the primary ahead of this year's presidential election.
President François Hollande hailed a "fine moral figure", a "socialist of the heart, reason and action".
"He expressed his convictions with firmness and sometimes bluntly, always with sincerity," Hollande declared. "He was very demanding of justice and equality."
"Henri Emmanuelli confronted the storms without ever bending," commented Prime Minister Bernard Cazeneuve. "He had loyalty in his heart and his compass set to the left."
Former prime minister Alain Juppé, veteran figure of the rightwing Les Républicains party, said in a statement that Emmanuelli was "a man who was ready to assume his responsibilities to the very end".
Emmanuelli was a close ally of socialist President François Mitterrand and, after his death, a stalwart of the party's Left, leading the New World faction that called for more radical policies after Lionel Jospin's failure to reach the second round in the 2002 presidential election.
His conviction for involvement in illicit financing while party treasurer did nothing to harm his standing in the party, although it led to him being banned from holding public office for two years and an 18-month suspended prison sentence.
In 2005 he joined many leftwingers, and some on the Right, in campaigning for a "no" vote in France's referendum on the European Union's Maastricht Treaty.