Oracle has increased its bid for Retek again outbidding rival SAP in the tug-of-war for the retail software maker.

SAP upped its bid to US$11 a share yesterday, and Retek's board unanimously accepted the offer. Hours later, Oracle said it had further raised its bid to $11.25. Oracle already owns 5.5 million Retek shares, close to 10 percent of the 56 million total outstanding shares.

SAP announced a deal on 28 February to acquire Retek for $8.50 per share. One week later, Oracle launched a launched a $9-a-share bid. SAP's latest $11 bid offers Retek shareholders $616 million. Oracle is besting that with $630 million. On the last trading day before SAP launched its bid, Retek (RETK) shares closed at $6.

SAP said that the $11 bid was its best and final offer. Retek has never commented on Oracle's surprise bid.

Oracle is bidding on Retek to defend its position on the North American market, Oracle CEO Larry Ellison said. Furthermore, Oracle's customers have requested that the customers buy Retek, according to Ellison.

Retek sells software to retailers, including applications for operations management, supply chain planning and execution, merchandise planning, and product demand forecasting. It has more than 200 customers in 20 countries. Both Oracle and SAP want to break into the retail space.