French authorities have frozen bank accounts held by Gabon's President Omar Bongo, says a lawyer in a case against Africa's longest-serving head of state. The move comes after a Bordeaux court ordered President Bongo to return a payment made to him to release a jailed French businessman, Rene Cardona. He was freed after his son paid more than $580,000 (£400,000) into 72-year-old Mr Bongo's account, a court heard. Mr Bongo is thought to have more than $4m (£2.8m) in French bank accounts. In September, a court ruled the payment to Mr Bongo had been illegal. That verdict was confirmed at appeal on Monday. Jean-Philippe Le Bail, a lawyer for the jailed businessman's son, told AFP news agency on Thursday: "The accounts held by Omar Bongo in two French banks have been seized." Rene Cardona was imprisoned in 1996 after a business dispute with Mr Bongo, to whom he had sold a shipping and fishing firm. Mr Bongo has been a close associate of a string of French leaders but his relations with Paris have deteriorated in recent years amid legal challenges by anti-corruption activists. Source: BBC