London - Former Wales and British Lions star Gareth Thomas announced his retirement from all rugby with immediate effect on Tuesday, saying he could no longer give his full commitment to the sport.
Thomas, 37, who switched codes to play for rugby league outfit Crusaders two years ago, had been due to turn out for Wales in the upcoming Four Nations international against England this weekend.
Thomas, who last played for Wales' rugby union side in 2007 when he scored a try in his 100th and final international, was also a member of the British and Irish Lions squad which toured New Zealand in 2005.
"I have listened to and discussed this decision with many of my family and close friends," Thomas said.
"My mind has told me that the time to retire is now.
"If you can't give 100% to rugby then you can't do it justice. This is a sad day but I know that my time has come to an end as a player. My passion for the amazing game will never end or leave me, however."
The burly wing made worldwide headlines in 2009 when he announced publicly that he was gay, making him the first openly gay professional player in world rugby.
Oscar-winning actor Mickey Rourke is reportedly planning to play Thomas in a film about the former Cardiff winger's life.