While Mel C is a self-confessed fan of- she even took to Twitter to declare this - she has become increasingly troubled about the music business's rise of "inappropriate" imagery and believes the 'S&M' singer's behaviour is unsuitable for her younger fans.
Talking to the Daily Mirror newspaper, she said: "People have to take some responsibility because we've got to a point where the over-sexualisation of young children has gone too far. I think music is a big part of that. Women in music are extremely sexual and they have young fans. It is inappropriate.
"Rihanna has a responsibility and although culture's always changing, it's changed too much. It needs to be dealt with. It's reached saturation point, we owe it to our kids to protect them."
Rihanna's graphic imagery – which featured heavily in her 'S&M' video and included whipping reporters, dressing in a leather bikini and being tied up – has seen some of her most recent music videos banned in many countries. 'S&M' was banned in 11 countries because of its sexual content.
Mel C believes that if the 'California King Bed' hitmaker was a mother she wouldn't make so many X-rated artistic decisions.
"I love Rihanna, I think she's a f***ing brilliant artist, with great songs, a great record and she looks fantastic ... but she's not a mum. Maybe if she becomes one she'll feel different. I hope so anyway."
Despite the irony of Mel and her fellow Spice Girl members receiving criticism in the late '90s for being too sexual for their young fans, Sporty Spice insisted they would censor themselves if they felt something was wrong.
"It's a long time ago since the Spice Girls were first together and we were criticised for being sexual. Yes we wore crop tops, look how much has changed, but we always sat down as a group and if somebody felt something was inappropriate for our young fans, we did something about it. I think that's something young people in the music industry today, like Rihanna, should do now."
Mel C is about to release her latest solo album, 'The Sea.'