The Wall Street Journal reports that Lehman Brothers appears to have been the victim of a fraud in Japan that other media outlets put as high as $403m.

According to the newspaper, Lehman Brothers Japan loaned monies to a medical consulting company called Asclepius Ltd in the mistaken belief that the funds had been guaranteed by Marubeni, Japan's biggest petrochemical importer. Marubeni has said that it is also the victim of fraud, as the company's so-called 'guarantee' was forged. The matter has been reported to the police.

Lehman said in a statement that 'after we became aware of the fraud, we launched a fact-finding investigation and then  informed the appropriate authorities. We are confident that we undertook all the appropriate measures on the transaction and will commence legal action against Marubeni'.

In the meantime, Bloomberg reports that US regulator the Securities and Exchange Commission has launched an investigation into whether profit-hungry traders short on Lehman stock have spread false rumours about the firm in a successful bid to cause the company's share price to fall.

The Financial Times reports that Australian regulators have launched an investigation into the collapse of Opes Prime, a margin lending and private-client broking business which has closed after the discovery of 'irregularities' in some of its accounts. The firm is said to owe $600m to ANZ and $321m to Merrill Lynch. The newspaper also reports that Bank of America may be forced to back off selling its prime brokerage business, as the unit has apparently only received lukewarm interest from the likes of Barclays Capital and BNP Paribas.

Reuters reports that a US federal judge has issued a temporary order blocking Douglas Sharon, the former head of Bear Stearns' Boston office, from joining Morgan Stanley. Bear complained that, over the weekend before he resigned earlier this month, Sharon was in the office printing out confidential information. Bear said that 'the Boston office printed out so many thousands of client account statements that the office exhausted its entire storehouse of paper'.

Finally, The Wall Street Journal reports that the 9 members of Commerzbank's board saw their 2007 comp fall 25% to $27.7m. The newspaper also reports that Nicholas Teller, who runs the bank's corporates and markets business, is to step down in May.

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