Jerome Kerviel, former trader of French bank Societe Generale.

Paris - The French trader Jerome Kerviel, who was sentenced in May to three years in jail over trading that lost his bank billions of euros, won a court battle that will allow him to leave prison on Monday as long as he respects home curfew rules, his lawyer said.

Dismissing opposition from a prosecutor, an appeals court judge said Kerviel, convicted after losing Societe Generale 4.9 billion euros (R68 billion) in 2008 with a pileup of trades that went wrong, could walk free on September 8.

He will wear an electronic bracelet that will allow him to go to work during the day but will alert authorities if he tries to leave home between 8.30 pm and 7 am.

Kerviel, 37, has fought one legal battle after another against his former employer since the debacle, which came as high-flying bankers fell into disrepute during a financial crisis that sparked the worst global economic downturn since the Great Depression.

He was initially sentenced to five years in jail - two of them suspended - and to a fine of 4.9 billion euros.

That was later struck down after an appeal where he and his lawyers had argued that the bank turned a blind eye to his activity.

“He will devote some of his time to community work,” Kerviel's lawyer, David Koubbi, told reporters.

If Kerviel, who is eying work for an information technology consultancy, respects the curfew deal he will be eligible for conditional release next June, suggesting that he could serve just over a year behind bars in total, a judicial source said.

Other legal battles continue over the fines and financial penalties incurred by a speculative gamble that triggered a record loss at the French bank. - Reuters