The release of Oracle Migration Workbench for IBM DB2/AS400 has come soon after IBM's announcement of the first update of its Informix database.
In April, Oracle responded to IBM's purchase of database company Informix in a similar way - offering tools to facilitate migration from Informix to Oracle's 8i and 9i database software.
The latest move comes as new figures reveal that Oracle is facing the biggest threat to its database dominance so far, with competitors such as IBM and Microsoft chipping away at its market share.
In its most recent earnings report, Oracle said its database sales have fallen by 8%. This compares unfavourably with IBM, which reported 19% and 36% growth in the past two quarters respectively, and Microsoft, which said its database revenue has grown by more than 45% over the same period.
Analysts have partly attributed Oracle's loss of customers during the past year to the company's attempt to introduce a controversial new pricing plan. The scheme would have forced customers using servers with faster processors to pay more.
At the launch of the 9i database in the summer Oracle scrapped the pricing strategy and followed IBM and Microsoft's lead by charging by the number of processors, regardless of speed.
The database market has essentially become a three-way race. According to Dataquest figures, Oracle captured 33.8% of the total market last year, up from 31.4% in 1999. IBM increased its market share slightly, to 30.1% from 29.9% the previous year, while Microsoft's share grew to 14.9% from 13.1%. Sybase and Informix, were the largest among the other suppliers in the market.