A man connected to Societe Generale trader Jerome Kerviel is being held by the French police.
According to the French media, the man works at Fimat, a brokerage firm that was a division of Societe Generale and is now merged with Credit Agricole. The man is being questioned about his links with Kerviel.
Jerome Kerviel has been accused of being a rogue trader, responsible for losing Societe Generale 4.9 billion euros as a result of his unauthorised trades. He was set free on 28 January after being questioned by magistrates for two days, although he remains under judicial supervision.
Kerviel is currently being investigated for possible breach of trust, computer abuse and falsification. On Friday an appeals court will decide whether or not he should remain free.
The Paris prosecutor has said that Kerviel should be kept in detention and has made an appeal against his release on the grounds that he may try to flee.
Ulrika Weiss, a spokesperson for the prosecutor said, The entire mechanism of the fraud needs to be verified and for the moment we only have the evidence provided by Societe Generale, reports the BBC.
She continued, It is necessary to verify whether Kerviel profited personally