LONDON (Reuters) - A nearly two-year battle to take over UK-based broadcaster Sky SKYB.L could finally be settled in a quick auction this weekend, Britain's Takeover Panel said on Thursday.

FILE PHOTO: The Sky logo is seen on outside of an entrance to offices and studios in west London, Britain June 29, 2017. REUTERS/Toby Melville/File Photo

Rupert Murdoch's Twenty-First Century Fox FOXA.O, which already owns 39 percent of Sky, and rival Comcast CMSCA.O are locked in a contest for control of the European pay-TV operator in a deal worth at least 25.9 billion pounds ($34.3 billion).

Comcast currently has the upper hand in the bidding war after it made a 14.75 pound a share offer for Sky in July, which trumped an earlier 14 pound a share bid by Fox.

Sky’s independent directors are currently recommending Comcast’s higher offer to shareholders.

If neither bidder has admitted defeat by 1600 GMT on Friday, Sept. 21, then an auction will kick off.

Below are the details of how the auction will be conducted.

** The auction begins at 1600 GMT on Friday, Sept. 21. From this point, neither party may make a revised offer, nor may they change any other conditions of their existing offers.

** A maximum of three rounds of bidding will take place on Saturday, Sept. 22.

** In the first round, the bidder with the lowest offer, or the last bidder to revise its offer if both are the same, may make an increased bid. As things stand, that would be Fox.

** In the second round, the other bidder may make an increased bid. They will do so knowing what their rival has done in the previous round, a source close to the process said.

** If there is no increased bid in the second round, the auction ends here.

** Otherwise, both parties may increase their bids in a third and final round.

** In the final round, each party may make its bid conditional on the other party also making a bid in that round.

** Bids may only be made for a fixed cash price in pounds sterling.

** All three parties are forbidden from publicly announcing any increased bids during the process.

** By the evening of Saturday, Sept. 22, the Takeover Panel will announce the offers of the two parties. The rules allow for the suitors’ final bids to be equal.

** By 0600 GMT on Monday, Sept. 24, each bidder must make an announcement of its latest bid.

** By Thursday, Sept. 27, the bidders must publish a revised offer document, if they have revised their offers.

** By Oct. 11, the offers must be declared unconditional as to acceptances.

** The Panel did not set any rules or deadlines for Sky’s independent directors to decide whether to change their recommendation to shareholders following the end of the auction on Saturday.

** Hypothetically, if the auction concludes with Fox and Comcast making equal offers for Sky, Fox’s bid could be more attractive to Sky’s minority investors because the U.S. giant already owns 39 percent of Sky and would have the better chance of taking control of the broadcaster.

($1 = 0.7548 pounds)