US computer storage giant EMC Corp. offered 1.8 billion dollars on Monday for Data Domain in a bid to counter a rival offer for the data storage company from NetApp.

EMC, in a statement, said it was prepared to offer 30 dollars per share in cash for Data Domain, which NetApp offered to buy on May 20 for 1.5 billion dollars or 25 dollars per share in a cash and stock deal.

"EMC's all-cash proposal is superior to the proposed NetApp transaction providing Data Domain stockholders greater value and certainty," EMC said.

"EMC's all-cash offer represents a 20 percent premium to the cash and stock offer made by NetApp," it said.

The Massachusetts-based EMC said the acquisition of Data Domain would improve its ability to "deliver industry-leading next-generation disk-based backup and archiving solutions for customers."

The Santa Clara, California-based Data Domain was founded in 2001 and employs 800 people.

EMC is the world's leading information management and storage company.

NetApp specializes in data management and computer storage.

Data Domain shares rose by 16.51 percent to 30.70 dollars in after-hours trading in New York while EMC was down 1.77 percent at 12.20 dollars and NetApp gained 1.50 percent to 21.00 dollars.