Jérôme Kerviel, the rogue trader who lost French bank Société Générale €4.9 billion (£3.8 billion), will learn today if he is to be released from jail after a French court was told that his colleagues at the bank helped him to conduct fictitious transactions.

The Paris Appeal Court will rule on his bail application after hearing claims by Mr Kerviel that he used his manager's computer at the ailing French bank to take unauthorised positions as he staked €50billion on European futures markets.

The 31-year-old trader, who faces charges of breach of trust, fabricating documents and illegally accessing computers, also told investigators that Thomas Mougard, his assistant, inputted fictitious deals on his orders, according to court documents.

Mr Mougard denied the claims, as did Eric Cordelle, the manager of the Delta One derivatives-trading desk, where Mr Kerviel was employed.

Rogue traders' profit boosted SocGen bonuses

Jerome Kerviel's lawyer claims executives at the French bank benefited from the successful investments of the rogue trader

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Multimedia

• Full coverage of the SocGen scandal

• Blog: Charles Bremner on SocGen

• Video: Patrick Hosking on the impact of fraud

BACKGROUND

• Who Knew What and When?

• SocGen director probed over €100m share sale

• Ex-SocGen risk auditor calls systems a sham

Related Links

• SocGen rogue trader seeks early release

• SocGen missed 75 warnings on trader Kerviel

The trader's comments appear to contradict SocGen's claims that he was a Machiavellian genius who hid his activities from other staff. His comments seem intended to lend weight to his argument that he acted with the tacit approval of bank executives, according to lawyers. If Mr Kerviel's claims are proved, they will increase pressure on Daniel Bouton, SocGen's embattled chairman, to resign.

However, the claims could rebound against Mr Kerviel as he seeks to be freed from La Santé Prison in Paris, where he has been held on remand for more than a month. Prosecutors exploited his comments, which he made in response to questions from Renaud van Ruymbeke and Françoise Desset, the magistrates leading the inquiry, in an effort to demonstrate that, if freed, Mr Kerviel could liaise with witnesses or accomplices.

According to documents read out in court, Mr Kerviel told magistrates that he took positions of “€500million or €600million at the desk of his direct superior, Eric Cordelle, and in his presence”. The maximum authorised ceiling for the desk was €125million.

Mr Kerviel said that he unwound these positions within a day or transferred them to his own computer. When he maintained the positions for longer than a day, it was without Mr Cordelle's knowledge, he added.

Mr Cordelle rejected the broad thrust of Mr Kerviel's allegations but admitted seeing him use a junior colleague's computer to take an unauthorised position “for a few hours”.

Mr Kerviel also sought to implicate Mr Mougard. Questioned by investigating magistrates, Mr Mougard admitted inputting fictitious orders on behalf of Mr Kerviel. But he said Mr Kerviel had told him these were meant to cover out-of-hours transactions, and never mentioned the multibillion-euro stakes on stock markets.

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