The Asahi News Network has posted video of MtGox CEO Mark Karpeles' Tokyo press conference admitting 850,000 bitcoins — worth nearly half a billion dollars — held by the exchange are gone, and that the firm is filing for bankruptcy.

"We have lost bitcoins due to weaknesses in the system," the France-born Karpeles said in Japanese according to the AFP. "We are really sorry for causing trouble to all the people concerned," he said, before bowing deeply.

MtGox was once the world's largest bitcoin exchange. Federal investigators in both Japan and the U.S. have launched probes into possible criminal conduct there.

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