Canberra confirmed the shock release of the star English halfback on Tuesday afternoon, after the 26-year-missed training that day.
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Williams had been speaking to the club about a release for weeks with his contract due to expire at the end of next season.
Unable to return home with his pregnant girlfriend due to the Covid-19 pandemic, Williams had been left in a tricky position trying to negotiate terms.
Taking to social media on Tuesday night, Williams responded to claims he 'dumped the Raiders by text'.
Responding to a Fox Sports tweet, Williams claimed he never wanted to be released immediately and was negotiating for the move at the end of the season.
He also claimed he hadn't signed the release form yet.
"I text to explain my mental wellbeing to the welfare manager?" Williams tweeted.
"I asked for a release weeks ago for the end of the season.
"Not once did I ask for an immediate release but instead of supporting me the club kicked me out the door."
Raiders release statement
In a statement, the Raiders said Williams phoned the club to say he would not be up to playing against the Sydney Roosters on Saturday.
Williams' partner Charlotte is also pregnant and the couple want to be with family in England when the baby is born.
While recognising the personal struggle Williams is facing, the Raiders finally found the situation untenable.
"George and his partner have asked on a number of occasions for a release to return to England to be closer to their families and we've decided to grant their request," Raiders CEO Don Furner said.
"George withdrew from training today and from the game this weekend which highlighted to the club the seriousness of George's request.
"Over the past several weeks we have supported George and provided him with the best welfare support we could, however as a club we felt that his position at the club moving forward became untenable."
The release of Williams has freed up salary space for the Raiders for the remainder of the season and in 2022.
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