Representatives for Lehman Brothers want to question the so-called London Whale in connection with a lawsuit accusing JPMorgan Chase (JPM) of hastening the investment bank's collapse.

Bruno Iksil, an former JPMorgan Chase employee who worked for the company in London, "played a greater role in events underlying this litigation" than Lehman had previously known, the defunct company and a committee of its unsecured creditors claimed in court papers filed Wednesday in Manhattan bankruptcy court.

The creditors asked Judge James Peck for permission to ask French authorities to compel testimony from Iksil, a French national whose practice of allegedly mismarking trades contributed to an "unjustified multimillion collateral call by JPMorgan to Lehman" in September 2008 - days before the investment bank's bankruptcy filing.

According to Lehman, a report published by JPMorgan Chase in January that reviews a $6.2 billion loss last year by the company's chief investment office shows that the office "played a vital role" in managing JPMorgan Chase's relations with trading partners, including Lehman.

Lehman filed a lawsuit against JPMorgan Chase in May 2010, charging that JPMorgan Chase's demands for billions of dollars of additional collateral and a refusal to return that collateral in the run-up to Lehman's implosion impeded the investment bank's ability to survive financially.

"That JPMorgan would run roughshod over Lehman's objections and insist on getting collateral immediately based on marks that were so quickly seen to be erroneous provide a window into JPMorgan's mindset and operating procedures the week prior to Lehman's bankruptcy: Get cash now, ask question later," Lehman wrote in Wednesday's filing, which was first reported by Reuters.

JPMorgan Chase spokesman Joe Evangelisti declined to comment.

Iksil, whose outsize bets earned him the "London Whale" nickname, also is reportedly the focus of the Senate Permanent Subcommittee on Investigations, which is said to be looking into messages sent by Iksil to superiors that may have tried to warn them the bank had misplaced its bets.

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