(Recasts with ESPN also submitting bid, NBC expected to bid; adds details of deal)
By Ronald Grover
LOS ANGELES, Jan 17 (Reuters) - Fox, CBS and ESPN have submitted bids for the rights to broadcast as many as eight Thursday night National Football League games, three people familiar with the bidding process told Reuters, as bidders began assembling for what is expected to be a highly contested auction.
NBC, which already broadcasts NFL games on Sunday nights, is expected to join the bidding by Friday night, when bids are due, according to one of the people.
Fox, owned by 21st Century Fox Inc, CBS, Comcast's NBC and Disney's ESPN sports channel were among TV networks that the NFL has invited to join the bidding process.
Based on the reported $950 million that NBC pays for its package of 19 NFL Sunday night games, an eight-game lineup could be worth $400 million or more.
The bids may come in lower because the league wants Thursday night games simultaneously televised on its own NFL Network cable channel along with the winning bidder's network, according to two of the people.
Representatives for Fox, CBS and NBC did not return requests for comment. An ESPN spokesman declined comment. The NFL also would not comment.
The NFL is seeking bids for a single season, starting this September, people familiar with the matter have said, with the likelihood of extending the contract after its first year. The league will determine how many Thursday night games it will offer based on the specific proposals it receives.
The football league is seeking bids for as many as eight of the games now exclusively telecast on the NFL Network on Thursday evenings, in an effort to get higher ratings and boost the match-ups' prominence.
The league wants to boost ratings for the Thursday night games to give them the same profile the NFL enjoys for its Sunday and Monday match-ups, according to a person with knowledge of the NFL's thinking.
NFL Network's Thursday night games were viewed by an average of 8 million viewers for a 13-game schedule in 2013, a 10 percent boost from 2012 but well below NBC's average 21.5 million viewers for its Sunday night contests. (Writing by Edwin Chan; Editing by Leslie Adler)