Software firm Oracle Corp. (NASDAQ: ORCL) filed suit against its rival SAP AG on Wednesday, accusing the competitor of stealing intellectual property to offer cut-rate services for its products.

In a suit filed in the San Francisco Division of the U.S District Court, the world's largest database maker said its German rival gained unauthorized access to its private networks, copying copyrighted programs.

This case is about corporate theft on a grand scale,'' Oracle said in the complaint. Oracle brings this lawsuit after discovering that SAP is engaged in systematic, illegal access to - and taking from - Oracle's computerized customer support systems.''

The Redwood City, Calif.-based software manufacturer ha spent over $20 billion buying companies, including PeopleSoft, Siebel and Hyperion to challenge SAP, the leader in business-management software.

Oracle shares closed up 1.87 percent at $18.51 on the Nasdaq, while SAP shares listed on the New York Stock Exchange were down .22 percent at $46.26.