WASHINGTON » A long-standing competition worth tens of billions of dollars to build a new Air Force refueling tanker has become entangled in a glitch after the Air Force mistakenly provided the rival companies sensitive information that contained each other’s confidential bid.

Chicago-based Boeing Co. and the European Aeronautic Defence and Space Company (EADS), parent of Airbus, are in an intense competition for a $35 billion contract to build 179 new Air Force tankers based either on the Boeing 767 jetliner or the Airbus A330.

The Air Force confirmed late Friday that because of a clerical error the Air Force accidentally provided Boeing with detailed proprietary information about the EADS bid and corresponding information to EADS North America concerning the Boeing bid.

"It was a clerical error and involved a limited amount of source selection information," Air Force spokesman Col. Les Kodlick said in a telephone interview. Kodlick declined to be more specific about what data had been transmitted.

Source selection information is data critical to the Air Force’s making a decision on which bid to select and could include technical data about the competing aircraft as well as financial information. The Seattle Times, which first reported Friday on the Air Force mixup, said the data included crucial pricing information on the competing bids.

Kodlick said the incident "will not delay" the awarding of the contract, which had been expected before year’s end but recently had been postponed until early next year. Kodlick said the postponement was not related to the disclosure of proprietary data.

It was not clear what use — if any — the two companies made of the information they received, reportedly on a computer disk.

"As soon as it happened and they received (the information), they recognized the errors and contacted the Air Force contracting officers," said Kodlick. He said the Air Force has taken steps "to make sure both companies have access to the same information."

But if the information included price data, it could have an impact on each company’s final bid proposal. Pricing has been a key issue in the competition. Last summer, Boeing CEO Jim McNerney expressed concern in a meeting with securities analysts that his company might be underbid by its European competitor.

The Air Force is reviewing how the disclosures occurred and is "taking steps that it doesn’t happen again," said Kodlick.

Sen. Maria Cantwell, D-Wash., who was briefed Friday on the incident, called the mix-up "an inexcusable mishandling by the Air Force of very sensitive, proprietary data" and was concerned that it might delay the contract decision, according to the Times.