Gregan was told that he had no future at Leeds when Dennis Wise took over in October, and he recently completed a loan deal with League One club Oldham, who have now offered him a permanent contract at Boundary Park.
Gregan was criticised by Wise yesterday after failing to return to training at Thorp Arch after the conclusion of his loan.
The defender was due to link up with his Elland Road team-mates on Tuesday morning, but he stayed away despite being selected for a behind-closed-doors reserve match.
Wise said: "He failed to turn up for a reserve game. I'm not happy. It's not the right way to act."