Relations have reportedly been strained between Betts and Millward

Relations are thought to have become strained between Betts and head coach Ian Millward after Betts allegedly refused to coach the academy side.

Millward replaced Betts as Wigan coach six months ago but the 36-year-old remained as the Australian's assistant.

Betts refused to give a reason for his resignation, except to say: "It will come out in the fullness of time."

Wigan also refused to discuss the details of Betts' departure.

Wigan issued a press release earlier this month claiming Betts had refused to take charge of their academy team following Adrian Lam's return to Australia.

Betts joined Wigan from amateur side Leigh Rangers in 1986 and was an integral part of the team that dominated British rugby league in the late 1980s and early 1990s.

He joined the newly-formed Auckland Warriors in 1995 but returned to Wigan three years later and scored the first try at the JJB Stadium.

He cut his coaching teeth with the academy team and became first team coach when Mike Gregory was taken ill after the 2004 Challenge Cup final.

Betts has been linked with a move to rugby union side Gloucester, who are thought to be looking for a defensive coach.