Former Wales international Gareth Thomas has joined rugby league player Keegan Hirst in expressing his "upset" at the Catalans Dragons' decision to sign Israel Folau.
Folau, who was sacked last May by Rugby Australia following anti-LGBT posts on social media, signed on a one-year contract with the Super League side on Tuesday.
The 30-year-old dual-code international reached a settlement with Rugby Australia in December having sued for £7.4m on the grounds of religious discrimination.
Hirst, who is Britain's only out professional gay rugby league player, said he was "shocked and disappointed" with the Super League side.
Thomas, himself a former dual-code international but who made his name in rugby union, is gay and said he will refuse to watch any matches involving the Australian.
"So Folau has joined the Super League. Really upset by this as the game, players, and fans were so good to me," Thomas tweeted.
"All I hope is that as much as Folau wanted his right to speak, then players and fans alike are aloud (sic) their right to respond. I will never watch him."
In a statement explaining their decision to allow Folau's registration, the RFL said: "However distasteful his previous comments, we don't believe that, under our current regulatory framework, these can prevent his participation in the sport."
Super League executive chairman Robert Elstone has criticised the signing, and revealed he "made Catalans Dragons aware of those views" before the deal was completed.
Shortly after Folau's signing was confirmed, fellow Super League side Wigan Warriors announced their game against Catalans Dragons on March 22 would be 'Pride Day' as the Warriors "look to support the LGBTQ+ community".
Robbie de Santos of LGBT equality charity Stonewall said: "Our Rainbow Laces campaign is dedicated to changing attitudes so that sport is inclusive of all. To help us in that mission, we need role models from all sports to speak up for equality and challenge prejudice.
"Folau's remarks also perpetuate a myth that faith and LGBT inclusion cannot coexist. Faith is a big part of many LGBT people's lives, and acceptance as part of a faith community can be incredibly powerful. We hope Folau reflects seriously on this.
"It's encouraging that the Rugby Football League has spoken out about the importance of inclusion and tackling offensive comments in sport. The more players, fans, clubs and organisations that stand up for equality in sport and society, the sooner we kick discrimination out and make sport everyone's game."