The former manager, who left the club a year ago, is understood to have rejected a £4million compromise offer to settle – a major obstacle in Barry Moat completing the takeover of the club.
Moat’s intention has always been to appoint Alan Shearer, a friend, to the position he briefly filled at the end of last season.
But, given the loss of so many players during the transfer window, Newcastle have performed well under the coaching of Chris Hughton and Colin Calderwood.
Keegan’s case is being examined by an independent Premier League arbitration panel at which the former England manager has given evidence.
Keegan has claimed that he was effectively forced out of his role having allegedly had new players imposed upon him, while Newcastle’s counter-argument is that he breached his contract, which still had three years to run.