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Schumacher, 45, regarded as one of the European technology industry's most outspoken CEOs, dramatically tendered his resignation during yesterday's meeting of the company's supervisory board.

The timing of the move is surprising, say analysts, not only because it was so unexpected, but also because Infineon appeared to have turned the corner of late after nine straight quarters of losses.

Infineon, which for now is being run by supervisory board chairman Max Dietrich Kley on an interim basis, did not give a reason for Schumacher's departure.

But some observers immediately questioned whether the resignation might be related to the ongoing inquiry on both sides of the Atlantic into possible price-fixing between three memory chip-makers, including Infineon.

European and US trade regulators are examining whether Infineon colluded with Samsung Semiconductor of South Korea and Micron Technology of the US to raise prices in late 2001 and early 2002, after a period of steadily falling prices.

However, sources close to Infineon suggested that Schumacher had been ousted because of his management style. "The main issue in this dispute was Schumacher's leadership style, which was criticised by many people as being overbearing," IG Metall, a major German union, said in a statement.

Schumacher in the past has been sharply critical of Germany's high taxes and rigid labour laws, and one Infineon executive told the New York Times that the CEO had clashed with other executives over his determination to cut costs by sending more manufacturing tasks and back-office jobs offshore.