Basell has until Wednesday to top bid for Huntsman Corp.

Dutch company Basell has until Wednesday to increase its bid for chemical company Huntsman Corp.

Basell, controlled by U.S. industrialist Len Blavatnik's Access Industries Inc., made the first bid for Huntsman last week, but private equity firm Apollo Management LP quickly offered a higher price and then topped its own offer Sunday, either to pre-empt a counteroffer or impress the Huntsman board.

Basell gets three days to match or top any offer for Huntsman, moving its deadline to the close of business Wednesday, spokesmen for Huntsman, Basell and Apollo confirmed.

Huntsman wasn't commenting on the bidding war, and Basell wouldn't say if it was preparing a higher bid.

"We delivered notice to Basell on Sunday concerning the Hexion bid," Huntsman Corp. spokesman Russell Stolle said Tuesday. "That notice entitles but doesn't require Huntsman to terminate the Basell agreement after the expiration of three business days."

Apollo, through its Columbus, Ohio-based Hexion Specialty Chemicals Inc. unit, raised its bid by 2.7 percent Sunday even though its earlier offer was judged superior to Basell's. The higher bid was made public Monday.

Apollo increased the offer to $28 from $27.25 a share, or more than $6.5 billion for all outstanding shares of Huntsman, which went public in February 2005.

Basell had offered $25.25 per share.

Anyone buying Huntsman also would assume about $4 billion in debt. The company is based in Salt Lake City but operates from the Houston area.

Huntsman Corp. generates about $10.6 billion in annual revenue, according to the latest quarterly figures from financial data provider Capital IQ.

The bidding has buoyed Huntsman shares, which dipped 18 cents to $27.89 in trading Tuesday.