Boeing Co said on Thursday that it was deeply disappointed that top rival EADS was trying to win more time to prepare a bid for the Pentagon's multibillion-dollar refueling aircraft contract.

The company also said the World Trade Organization's recent ruling that EADS benefited from illegal subsidies on its commercial aircraft programs requires Boeing to review all of our options for going forward while we wait for a final determination on a deadline extension.

A Boeing spokesman declined to elaborate on the company's options.

The Pentagon said on Wednesday that it would extend the deadline for bids on its tanker contract by 60 days if Europe's EADS formally pledges to bid against Boeing.

EADS has said it would consider the 60-day extension, but also said it had told U.S. officials it needed a 90-day extension to the May 10 deadline to prepare a bid.

We are deeply disappointed with EADS-Airbus efforts to further delay this vital war-fighting program and tilt the U.S. procurement process in its favor, Boeing said in a statement.

EADS-Airbus has been fully engaged in the competition for four years and was always expected to provide the vast majority of its team's work content, the company said.

The Pentagon's announcement of a 60-day extension came a day after President Barack Obama vowed to run a fair and open competition for the new aerial tankers.

Boeing backers in Congress have complained that the Pentagon was bending the rules to placate Europe in the contest that could be worth as much as $50 billion.

EADS is deciding whether to bid alone after its U.S. partner, Northrop Grumman , pulled out of the race.

Boeing remains fully prepared to submit a competitive proposal by the May 10 deadline originally set by the Air Force, the company said.

(Reporting by Kyle Peterson; editing by Gunna Dickson and Lisa Von Ahn)