The supervisory board of WestLB, one of Germany's biggest state-owned banks, may sack all seven of its top managers in punishment for keeping silent about stock-trading blunders, banking sources said Wednesday, according to dpa. A mass sacking would be without modern precedent in the world of big German banks, where highly paid executives hold jobs long term. The supervisory board, representing the owners, the state of North Rhine Westphalia and its savings banks, was to hold a meeting on Thursday at short notice, shareholder sources said. Of the seven, one handed in his resignation two weeks ago and another has already been told his contract will not be renewed, while news media have already said chief executive Thomas Fischer faces pressure to go. The other four had earlier been thought likely to keep their jobs. The sources said a report by auditors to German federal regulators had been obtained in recent days and it suggested the executives may have failed in their collective duty as board of management to inform the main board of the losses. WestLB says it lost 243 million euros (335 million dollars) in securities trading in the first six months of this year when speculation backfired, stock traders broke rules and secret bank investment strategy was leaked. German media, Spiegel Online and the newspaper Rheinische Post, said new hirings would replace the whole top management.