The Toshiba Corporation's troubled US nuclear branch Westinghouse has filed for bankruptcy protection, as it wrestles with multi-billion dollar losses and claims of accounting fraud. 

Earlier on Wednesday, Toshiba's board approved the Chapter 11 filing in a US court, which temporarily shelters struggling firms as they try to restructure their operations and debts. Toshiba had previously warned it was facing a write-down topping 700 billion yen (6 billion US dollars), at Westinghouse. The firm has suffered new project delays and cost overruns.