TOKYO, June 10 (Reuters) - Western Digital Corp plans to raise its offer for Toshiba Corp's prized semiconductor unit to 2 trillion yen ($18 billion) or more, a person familiar with the matter said, marking a last-ditch effort to clinch a deal that both companies consider vital.
The U.S. chipmaker's new offer, to be presented by Thursday when the struggling Japanese conglomerate is to decide a preferred bidder for its Toshiba Memory Co unit, will be in the form of a debt purchase, to avoid antitrust concerns over the proposed purchase of the world's second-largest producer of NAND memory chips, the person told Reuters on Saturday.
A spokesman for Western Digital had no comment. Toshiba could not immediately be reached for comment.
Toshiba had set a 2 trillion yen threshold for the sale. It is rushing to find a buyer to cover billions of dollars in cost overruns at its now-bankrupt U.S. nuclear business Westinghouse Electric Corp.
Western Digital has been bidding in a consortium led by a Japanese government-backed fund, but Toshiba on Friday expressed dissatisfaction with that bid.
Toshiba has been favouring a rival bid from U.S. chipmaker Broadcom Ltd, which has partnered with U.S. private equity firm Silver Lake to offer 2.2 trillion yen, people familiar with the matter have told Reuters. (Reporting by Makiko Yamazaki in Tokyo; Additional reporting by Liana B. Baker in San Francisco; Editing by William Mallard)