NEW YORK ( TheStreet) -- JPMorgan Chase ( JPM) and Citigroup ( C) helped cause the failure of Lehman Brothers by demanding more collateral and changing guarantee agreements, says a Bloomberg reading of a court-ordered report on the biggest bankruptcy in U.S. history.

"The demands for collateral by Lehman's lenders had direct impact on Lehman's liquidity," said Anton Valukas, the bankruptcy examiner, in the document filed Thursday. "Lehman's available liquidity is central to the question of why Lehman failed."

Danielle Romero-Apsilos, a spokeswoman for Citigroup, said in an e-mailed statement to Bloomberg that the bank is reviewing the report, and that a preliminary analysis shows the examiner "has not identified any wrongdoing on Citi's part."

The report has pulled up former Lehman CEO Richard Fuld and ex-Chief Financial Officer Erin Callan, among others, for certifying misleading statements about the bank's finances.

Valukas said Fuld was "at least grossly negligent in causing Lehman to file misleading periodic reports" while its risks were rising because of long-term assets financed with short-term debt.

Disputing the examiner's allegation, Fuld's lawyer, Patricia Hynes, told Bloomberg, "Mr. Fuld did not know what those transactions were -- he didn't structure or negotiate them, nor was he aware of their accounting treatment."

Valukas also made a mention of Barclays ( BCS) purchase of Lehman's North American brokerage that a "limited amount of assets" belonging to Lehman were "improperly transferred to Barclays." He added that the value of the assets may not be "material."

Spokespeople for Barclays and JPMorgan spokesman declined to comment for Bloomberg.