A champion weightlifter has been accused of seducing and having sex with vulnerable women as young as 17 that he coached in his church-affiliated gym, while he was engaged to be married.

Rhyss Keane, 27, Australia's strongest man, has been accused of misusing his position of power as a coach with the Impact Christian church on New South Wales' central coast.

A 17-year-old woman was one of three to come forward and make disturbing allegations against the professional weight-lifter claiming he seduced his clients, sent them sexually explicit messages and images, and had sex with them behind his fiancee's back.

'He would ask me to press against his groin region, it was really manipulative and sort of controlling,' the 17-year-old girl, who used the name Jade, told A Current Affair.

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Rhyss Keane, 27, (pictured) Australia's strongest man, has been accused of misusing his position of power as a coach with the Impact Christain church on New South Wales' central coast

Details of Mr Keane's sordid affairs emerged the night before his wedding to Kayleigh (pictured on their wedding day)

The woman said she met Mr Keane at a power lifting competition when he spotted her and offered to be her coach.

She said his offer was a dream for a young, enthusiastic weightlifter.

Jade told A Current Affair it wasn't long before Mr Keane started to seduce her.

She said the 27-year-old sent her sexually explicit text messages including: 'Will you show me your panties before you come so I can eye **** you and know what you are wearing?'

Jade said alarm bells went off when Mr Keane asked her if she would get mad if he impregnated her.

'He seemed to be quite infatuated with getting me pregnant and I found that really strange. That's when I sort of stepped back a little bit and tried to evaluate what was really going on,' she said.

Jade said she consented to having sex with Mr Keane three times.

The woman said she met Mr Keane (centre) at a power lifting competition when he spotted her and offered to be her coach

Jade claims Mr Keane started to send her sexually explicit text messages including: 'Will you show me your panties before you come so I can eye **** you and know what you are wearing?'

Jade said alarm bells went off when Mr Keane asked her 'would you be mad if I got you pregnant?'

She claimed she was one of at least five women having an affair with the weightlifter, all while he was engaged to be married to another woman.

Details of Mr Keane's alleged sordid affairs emerged the night before his wedding to his now wife, Kayleigh.

Mr Keane issued an apology online after alleged details of his affairs broke.

He said he had a serious problem and was seeking professional help.

He said his wife knew the details when she married him, but he was ashamed and embarrassed.

Impact Gym, in Erina New South Wales, where Mr Keane was a trainer, offered counselling to anyone who needed it.

Jade's mother was shocked by the gym's response to Mr Keane's alleged affairs.

'I just was thinking "who does that to people, not just my daughter, but people" and I was quite disgusted they're affiliated with the church,' she said.