EMC Corp. (EMC), responding to a report that it plans to raise its offer to acquire Data Domain Inc. (DDUP), said its $30 a share offer is superior to a competing bid from NetApp Inc. (NTAP).

"We believe our $30 all-cash tender offer is superior," an EMC spokesman said. "We have not raised our bid and believe investors will prefer our all cash offer and vote against the NetApp-Data Domain merger agreement."

Earlier Friday, Reuters, citing people familiar with the matter, reported EMC plans to increase its bid for Data Domain to as much as $35 a share to win Data Domain or at least make the acquisition very expensive for NetApp.

Data Domain shares reacted tepidly to the report as many have already speculated a higher bid could surface. Shares were recently up 8 cents, or 0.24%, to $33.37. EMC gained 1% to $13.21, while NetApp rose 7 cents, or 0.4%, to $19.98.

EMC and NetApp are locked in a bidding war over Data Domain, which sells a technology used to reduce the amount of duplicated information in data centers.

Data Domain accepted a $25 a share cash and stock offer from NetApp in May, only to have EMC counter with a $30 a share all-cash bid. Then NetApp raised its bid to match EMC's offer, which was accepted by Data Domain as the superior bid. The NetApp offer is still a combination of cash and stock.

-By Jerry A. DiColo; Dow Jones Newswires; 201-938-5670; jerry.dicolo@dowjones.com