Mt Gox said on its website it had found 200,000 ‘forgotten’ bitcoins on March 7, a week after the Tokyo-based digital currency exchange filed for bankruptcy protection.

Online sleuths had noticed around 200,000 bitcoins moving through the crypto-currency exchange after the bankruptcy filing.

The exchange, headed by 28-year-old Frenchman Mark Karpeles, said the bitcoins were found in an old-format online wallet which it checked again after its filing.

It moved the 200,000 bitcoins from online to offline wallets on March 14-15 “for security reasons”.

“These bitcoin movements have been reported to the court and the supervisor by counsels,” it noted.

Many of Mt Gox’s 127,000 creditors, who feared they had lost their investments when the exchange filed for bankruptcy, are sceptical about what the exchange has said happened to the bitcoins it had. In its bankruptcy filing, Mt Gox also said $28 million was “missing” from its Japanese bank accounts.

Last Thursday, a US judge in Chicago overseeing a class action against Mt Gox revised a previous order, allowing some of the exchange’s bitcoin movements to be tracked.

“Today in court we got relief... specifically to track the 180,000 bitcoins which we’ve been monitoring. Hours later, Mt Gox claimed it ‘found’ these bitcoins,” Steven L. Woodrow, a partner at law firm Edelson, said. He is representing Illinois resident Gregory Greene, who proposed the class action over what he claims is a massive fraud. Mt Gox blamed the loss of 750,000 bitcoins belonging to its customers and 100,000 of its own on hackers.