Oracle has offered to buy middleware vendor BEA Systems for $17 per share in cash, a deal valued at $6.66bn.

Oracle said it had written to BEA's board of directors on Tuesday to make the offer, which represents a premium of 25 percent over BEA's closing share price on Thursday.

BEA was a pioneer in the market for Java application server software used to deploy business applications, competing with products like IBM's WebSphere. It has been rumoured to be an acquisition target on numerous occasions but managed to retain its independence.

"This proposal is the culmination of repeated conversations with BEA's management over the last several years," Oracle President Charles Phillips said today. "We look forward to completing a friendly transaction as soon as possible."

However, BEA executives were not quoted in the statement and there was no indication early Friday as to whether the company was open to being acquired.

Oracle said the acquisition would help it to beef up its own middleware suite, an important area for the company that is serving to link several families of business applications that it has acquired.

The company said it would protect the investments of BEA customers if the deal were to go ahead.

"Our continuing support commitment has been amply demonstrated with all of our previous acquisitions, including PeopleSoft and Siebel. BEA will be no different," Phillips said.