France's Societe Generale acted in an "absurd and uncivilised" manner in firing a London banker without proper notice, his lawyer told Britain's Supreme Court on Wednesday in pursuit of a claim worth over $16 million (9.9 million pounds).

Belgian Raphael Geys, who was managing director for European fixed income sales until being told to leave in 2007, has sued for some 12.5 million euros in a case that hinges on just when his contract ended and which has wider implications for the use of instant dismissal procedures in finance and other industries.

Neither Geys, who has already been awarded some 10 million euros, nor SocGen, France's second biggest bank, can expect much sympathy among a public fuming at breath-taking pay levels in a sector that has had to be bailed out by taxpayers.

But the case, to be heard until Thursday, is being watched closely by lawyers because it could reshape employment law if the court rules that "payments in lieu of notice", or PILONs, mark the end of a contract even if an employee is not given explicit notification that a payment is meant for that purpose.

For Geys, whose case has already been heard in lower courts, the question of whether his contract ended in December, when SocGen made a payment into his bank account, or in January, when the bank expressly told him that the cash was a PILON, is key to his claim to be owed further year-end bonuses and other sums.

David Cavender, Geys's lawyer, accused SocGen of "termination by stealth", telling the judges that employers were obliged to both pay and notify an employee before a contract could be considered as being terminated: "It's not an onerous requirement," he said. "That's what's odd about this case."

He argued that without explicit notification Geys, who was in court, might have gone skiing, for example, while unaware that he was no longer covered by employee insurance policies.

Ian Gatt, representing SocGen, argued that employment contracts are ended when PILONs are made into the bank account of employees: "The oddity of my learned friend's case is that a payment in lieu of notice itself needs a notice," he said.

"TOO EXPENSIVE"

Geys says that he only learned in early January 2008 that a payment of about 32,000 pounds made into his bank account the previous month was a PILON, intended to end the contract which had been told in person in November 2007 was to be terminated.

The payment was in lieu of notice to which he was entitled and was based on his annual basic salary of 150,000 pounds.

He says that his boss, Fred Desclaux, told him when he was fired on November 29, 2007 that he had to terminate Geys because he was "too expensive" due to the way his earnings were calculated.

Geys says gross revenues at his division more than doubled between 2005 and 2007 to around 440 million euros. He refused an initial offer of 7.9 million euros in contractual termination payments. Having been awarded about 10 million in lower court hearings, he is now seeking a full payment of some 12.5 million.

Legal experts are hoping the five Supreme Court judges will make their judgment before the end of the year.

"This is a very interesting case for all employers," said Jo Keddie, a partner at solicitors Winckworth Sherwood.

"If employers fail to discharge their contractual obligations properly in respect of PILON clauses, they will be exposed to claims to make good ongoing salary and benefit payments as well as any damages arising from their breach."

(Editing by Alastair Macdonald)