SAP said it would not comment until it had reviewed the 44-page lawsuit. Oracle''s lawsuit alleges that SAP resorted to illegal activity to maintain its leadership in the market for business applications software. The two software leaders are fierce rivals in the business software segment.

In its suit, Oracle has claimed that staff at a firm bought by SAP in 2005, TomorrowNow, had accessed Oracle''s computer network last year and illegally downloaded and assembled a storehouse of stolen Oracle intellectual property comprising copyrighted software and other material.

Oracle''s suit, lodged with a federal court in San Francisco, claims that part of SAP''s "illegal" competitive strategy against Oracle is based on the theft of this material.

The software was part of the Peoplesoft business that Oracle had acquired in 2005, one among a series of takeovers worth $20 billion by Oracle in the last three years, putting pressure on market leader SAP.

While SAP has managed to defend its market leadership in most areas, during the past six months the German company has performed below market expectations, while Oracle recently posted stronger than expected results, despite its huge investments in takeovers in the last three years.

Oracle and SAP have been battling for years for supremacy of the lucrative enterprise software market, estimated at $60 billion. During Oracle''s acquisitions, SAP offered Oracle customers a "safe passage" programme that would guarantee support for Oracle products with the help of companies like TomorrowNow.