Kazakh bank BTA said Thursday that exiled oligarch Mukhtar Ablyazov had embezzled at least $6 billion and also caused hundreds of millions in losses for foreign banks.
Ablyazov, a fierce critic of Kazakhstan's regime, was arrested last week in France on a warrant issued by Ukraine where BTA has subsidiaries.
A BTA spokeswoman estimated that British banks HSBC, Standard Chartered, RBS and Barclays were exposed to $500 million in losses.
Eight Italian banks including Unicredit, Banca Monte dei Paschi di Siena and Mediobanca, were left on the hook for $250 million.
The damage to French banks BNP Paribas, Societe Generale, Credit Agricole and BPCE was around $50 million, she added.
She also said Credit Suisse, Germany's Commerzbank and Wells Fargo in the United States were hit, but did not cite any figures.
Ablyazov "not only pushed our bank to the brink of bankruptcy, but also caused losses for international investors," said the bank spokeswoman.
She said the banks were cooperating in efforts to recover BTA's assets.
Societe Generale declined to comment, while the other French banks were not able to immediately respond to questions surrounding the case.
Once a minister and close to the Kazakh elite, Ablyazov fell out of favour and became a foe of strongman Nursultan Nazarbayev, who has ruled the ex-Soviet country for almost 22 years.
Ablyazov was jailed in 2002 in a move widely seen as a bid to silence him, but he was quickly pardoned and returned to finance where he had made his fortune, becoming chief executive of BTA in 2005.
The bank expanded rapidly but then hit problems when the global economic crisis rocked Kazakhstan's highly leveraged housing market in 2009.
Ablyazov fled to Britain that year amid accusations he stole billions of dollars in state and investor funds.
He left that country after being sentenced to 22 months in jail for contempt of court.
French authorities are to examine extradition requests before deciding whether to deport Ablyazov.
Kazakhstan does not have an extradition agreement with France, while authorities in Russia, where BTA also had operations, said they were also preparing a request to have Ablyazov handed over.