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BRUSSELS Jan 9 (Reuters) - The chief financial officer of BNP Paribas is under investigation by Belgian prosecutors looking into the lead-up to the collapse of Belgian-Dutch bank Fortis in 2008, Belgian business dailies De Tijd and L'Echo reported on Wednesday.
Lars Machenil, formerly with Fortis , would be the sixth person embroiled in a widening criminal investigation into the failure of Fortis, once one of Europe's largest banks, which was rescued and carved up at the height of the crisis in late 2008.
Both BNP Paribas and Brussels prosecutors declined to comment.
Shares of BNP fell 1.0 percent, to 45.26 euros, the fourth-worst performers on the STOXX Europe 600 banks index , up 1.4 percent.
"If confirmed, this would be obviously bad news for BNP Paribas," a Paris-based trader said. "The market could raise the question of replacing Machenil."
Machenil joined Fortis in 2000 and was the financial director at BNP Paribas Fortis from 2009 until last year.
Former Fortis chief executives Jean-Paul Votron and Filip Dierckx become the first directors to face criminal charges in Belgium over banking failures during the crisis, which also forced bailouts for Franco-Belgian Dexia and Belgium's KBC.
De Tijd and L'Echo said Brussels prosecutors are also looking into three other former senior Fortis figures, including Maurice Lippens, chairman from 1990 until 2008.
Fortis came unstuck after paying a top-of-the-market 24 billion euros to buy the Dutch operations of ABN AMRO just before the credit crunch struck.
Shareholder groups have complained Fortis repeatedly assured markets that it was healthy, its balance sheet was strong and that it would not be changing its dividend policy.
In September 2007, before a 13.4 billion euro rights issue, Fortis said that a 20 percent deterioration of the U.S. subprime market would only hit net profit by 20 million euros.
At the end of June 2008, it scrapped its interim dividend and sold new shares to prop itself up.
In early 2009, a special purpose vehicle purchased Fortis's mostly junk grade assets for 11.7 billion euros, against a face value of 20.7 billion euros.
A Dutch court found Votron and former chief financial officer, Gilbert Mittler, guilty in February of misleading shareholders from May to June 2008, but cleared Lippens. Both have appealed and the case is still pending.
Fortis was split up in October 2008. The Dutch nationalised Fortis's activities there. BNP Paribas bought a majority in Fortis's banking operations in Belgium.
The rump Fortis business, renamed Ageas, was left as an insurance group centred on Belgium.
($1 = 0.7705 euros) (Reporting by Philip Blenkinsop in Brussels; Additional reporting by Lionel Laurent and Blaise Robinson in Paris; Editing by Mark Potter)