According to the Daily Telegraph, both Standard Chartered - which employs more than 80,000 people globally - and HSBC have been ordered to hand over thousands of documents relating to the account holdings of Maan Al-Sanea by a New York court.
Both financiers will disclose personal information about Mr Al-Sanea's activities, as it is alleged that he defrauded his wife's family of billions of dollars from accounts in locations such as the UK, Switzerland and the Cayman Islands.
Furthermore, Bank of America and Citi are also now legally required to hand over papers regarding the man's transactions, meaning all four organisations appear likely to have to give evidence in the case.
Judge Jed Rakoff suggested that the banks may be liable for some of Mr Al-Sanea's alleged activity if they are found to have not taken "reasonable steps to ascertain who their customer was".
By Tony Aynsley