In a stunning revelation by a court-ordered investigation, it has come to light that JPMorgan Chase and Citigroup helped script the downfall of Lehman Brothers Holdings - the biggest bankruptcy in the US corporate history by demanding more collateral and changing guarantee agreements.

"The demands for collateral by Lehman's lenders had direct impact on Lehman's liquidity," said Anton Valukas, the officer investigating the bankruptcy in a Manhattan federal court.  

In a report that ran over 2000 pages and cost the exchequer $38 million also blamed former Lehman Executive and the auditor Ernst & Young of certifying misleading statements about the bank's finances. New York-based Lehman collapsed in September 2008 with $639 billion in assets.

The examiner also noted that Warren Buffett, who runs investment firm Berkshire Hathaway, was of the view that Lehman appeared not to be sincere enough to warrant his help.

Valukas also said of Barclays' purchase of Lehman's North American brokerage that a "limited amount of assets" were "improperly transferred to Barclays," and that the value of the assets may not be "material."