Former French Ligue 1 champions Bordeaux on Thursday said they will become an amateur club for the first time in almost 90 years after filing for bankruptcy.

They had announced earlier in the week that they would accept their relegation to the third-tier Championnat National by French football's financial watchdog, the DNCG.

Bordeaux, based in France's south-west, won the last of their six top flight titles in 2009.

They first turned professional in 1937.

The club needs to find 40 million euros ($43.6 million) to balance their books and had been in talks with the owners of Liverpool, Fenway Sports Group (FSG), before the American investors pulled out of negotiations earlier this month.

"On Tuesday, the club filed for bankruptcy with Bordeaux's commercial court, to be able to begin necessary restructuring," they said in a statement.

"The club had to give up asking to maintain its professional status" as it risked "heavy sanctions" if it presented a recovery plan to the DNCG that did not reflect its future financial reality.

Bordeaux were relegated to Ligue 2 in 2022, just 12 years after reaching the Champions League quarter-finals.

The town's mayor slammed the decision by Bordeaux's controversial owner Gerard Lopez, who has invested 60 million euros into the club since 2021.

"I've learnt with consternation the sudden and personal decision made by Gerard Lopez," Pierre Hurmic told AFP.

"It confirms the risky management that has led our club in the space of three years from the elite Ligue 1 to the amateur level," he added.

A host of well know players -- past and present -- have played for Bordeaux including World Cup winners Zinedine Zidane, Bixente Lizarazu and Christophe Dugarry, as well as Real Madrid midfielder Aurelien Tchouameni.

"I feel extremely sick like everyone who loves the club," 1998 World Cup winner Lizarazu said on Instagram.

"What's happing is unfortunately the result of disastrous football and financial management for many years," he added.

One consequence to the move is that the club's academy will close and a host of professional players will leave the outfit.

The new Championnat National season begins on August 16 with Bordeaux expected to play at their 42,000-capacity Matmut Atlantique home, France's sixth biggest stadium, for the campaign.