A former Lehman Brothers Holdings Inc executive warned months before the bank's collapse that senior management was potentially misleading investors and regulators about the value of the firm's assets, the Wall Street Journal reported on Saturday.

In a May, 2008 letter addressed to then-Chief Financial Officer Erin Callan, Chief Risk Officer Chris O'Meara and others, Lehman senior vice president Matthew Lee said the firm had tens of billions of dollars of unsubstantiated balances, which may of may not be 'bad,' or non-performing assets, the paper reported, citing the letter.

Lee, who reported to the firm's global financial controller, singled out the accounting at the firm's Mumbai office, citing a very real possibility of a potential misstatement of material facts being efficiently distributed by that office, according to the paper.

The alleged misstatements may have violated Lehman's internal code of ethics, Lee said in the letter, the paper reported. Lee was fired a few days after he wrote the letter, and later got a severance agreement that prevents him from filing whistle-blower complaint, the paper said.

The allegations mirror similar complaints by investors and analysts at the time, including Greenlight Capital Inc's David Einhorn, who questioned the bank's write-up of the value of a power plant in Mumbai, the paper reported.

Lehman filed for bankruptcy protection in September 2008.

On Friday, Senate Banking Committee Chairman Chris Dodd asked the Justice Department to look into possible wrongdoing by Lehman executives who may have used accounting tricks to hide the true state of the firm's financial condition.

Parts of Lee's letter were included in a 2,200-page report by the court-appointed examiner released on March 11.

(Reporting by Ann Saphi, editing by Vicki Allen)