BUZZ-Petrobras SA: Brazil takes legal action against contractors
** Brazilian state-run oil company's U.S.-listed shares down 4 pct at $8.89 premarket
** Brazil's comptroller general opens cases on Wednesday against 8 engineering conglomerates, suspected of bribery and fraud in deals with Petrobras
** Scandal has intensified scrutiny of corporate governance at Petrobras
** Some minority shareholders have complained of lax oversight and outsized government influence
** Up to Wednesday's close, stock had fallen 33 pct this year due to corruption scandal and fall in global oil prices
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