(Adds reaction from Northrop Grumman, Raytheon, paragraphs 6-8)

WASHINGTON, Jan 21 (Reuters) - The U.S. Air Force confirmed on Wednesday that it would re-evaluate bids it had received for a long-range radar system, resolving protests filed by Lockheed Martin and Northrop Grumman about a contract won by Raytheon in October.

The Air Force said a new round of discussions with bidders on technical evaluations and pricing analysis may take about four months. It said it was taking the action after feedback from the Government Accountability Office, the congressional agency that reviews federal contract protests.

Reuters first reported the news on Tuesday.

"Depending on the responses, the additional discussions may result in a new source selection decision," said Air Force spokesman Justin Oakes.

Lockheed welcomed the Air Force's decision to address concerns raised about the competition for the Three-Dimensional Expeditionary Long-Range Radar (3DELRR).

A spokesman for Northrop Grumman said: "We are pleased that the Air Force has indicated it will take corrective action to ensure a robust competition that should enable the Department to obtain the best solution for our warfighters.

"We remain confident in Northrop Grumman's ability to offer a capability that meets the Air Force's critical mission requirements at an affordable cost," Randy Belote, vice president of strategic communications, said in a statement.

At Raytheon, Integrated Communications Manager Mike Nachshen said: "We were informed by the USAF of their decision, and are currently evaluating our options. Raytheon remains confident in our solution and we're eager to move forward and deliver this much-needed 3DELRR capability to the US and its friends and allies." (Reporting by Andrea Shalal; Writing by Doina Chiacu; Editing by Bill Trott and Eric Walsh)