Billy Vunipola is facing potential disciplinary action from the Rugby Football Union and Saracens after supporting Israel Folau’s controversial anti-gay comments by claiming “man was made for woman”.

The RFU will summon Vunipola to question him over a social media post made in which he defends Folau, who is facing the sack by Rugby Australia for his claims that “hell awaits” gay people. Saracens have stated they will deal with the “very serious matter” internally.

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Compounding the RFU’s headache, the No 8’s post was liked by fellow England internationals Manu Tuilagi, Nathan Hughes, Nick Isiekwe and Courtney Lawes, who replied with his own message defending Vunipola’s decision to offer his opinion. It remains to be seen whether they and other Premiership players, including his childhood friend and Wales No 8 Taulupe Faletau, who also “liked” the post, will face further action.

Vunipola had initially “liked” Folau’s Instagram message and went on to explain he had received three phone calls instructing him to backtrack before claiming the Australia full-back was saying only “how we live our lives needs to be closer to how God intended them to be. Man was made for woman to pro create [sic] that was the goal no?”

All members of England’s elite player squad – of which Vunipola is one – are required to adhere to a code of conduct in accordance with the RFU’s values and he is now facing the possibility of being charged with conduct prejudicial to the interests of the game under the union’s Rule 5.12. An RFU spokeswoman said: “Rugby is an inclusive sport and we do not support these views. We will be meeting with Billy to discuss his social media posts.”

Vunipola has also reportedly been dropped by Channel 4 with a spokesperson for the channel adding: “These views are incompatible with our values as an inclusive broadcaster and in light of this Billy Vunipola won’t be used as a contributor in Channel 4’s rugby coverage.”

Vunipola’s full Instagram post read:“So this morning I got 3 phone calls from people telling me to ‘unlike’ the @izzyfolau post. This is my position on it. I don’t HATE anyone neither do I think I’m perfect. There just comes a point when you insult what I grew up believing in that you just say enough is enough, what he’s saying isn’t that he doesn’t like or love those people. He’s saying how we live our lives needs to be closer to how God intended them to be.

“Man was made for woman to pro create that was the goal no? I’m not perfect I’m at least everything on that list at least at one point in my life. It hurts to know that. But that’s why I believe there’s a God. To guide and protect us and forgive us our trespasses as we forgive those who trespass against us.”

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The RFU refused to confirm one of the phone calls came from the union but it came under increasing pressure to act after the outcry over Folau’s comments. The RFU has worked with the LGBT charity Stonewall for the last two years, backing its rainbow laces campaign and recently “restated its ongoing commitment to diversity and inclusion at all levels of the game” as part of its four-year strategic plan. Stonewall responded to Vunipola’s post with a statement that read: “Faith is often used to justify anti-LGBT views and attitudes. This is wrong and perpetuates a myth that faith and LGBT inclusion cannot coexist.”

Saracens, who have named Vunipola on the bench for Saturday’s match at Bristol, also condemned the post. A club statement read: “Saracens proudly embraces diversity and warmly welcomes everyone to the club regardless of race, gender, religion and sexual orientation. Our sport is open to all and we strive for it to be free from all forms of discrimination. We recognise that people have different belief systems and we expect everyone to be treated equally with respect and humility.

“As representatives and role models, Saracens players have a responsibility not only to themselves but to the club and wider society. Billy Vunipola’s recent social media posts are inconsistent with this and we take this matter very seriously. It will be handled internally.”

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A Premiership Rugby spokesperson added: “Inclusivity is one of the core values of Premiership Rugby and we condemn any behaviour that encourages discrimination. We are committed – with the RFU – to keeping rugby in England inclusive and some of the highlighted social media posts over the last day or so are in opposition to this.

“We were delighted to support Stonewall’s Rainbow Laces campaign earlier in the season and welcome the opportunity to continue that next season.”