Katy Perry's parents predict her fiance Russell Brand is becoming "a great man of God".

The 'Teenage Dream' singer's mother Mary and father Keith Hudson - who are both evangelical Christian pastors - believe the former drug addict and womaniser is undergoing a "transition" and will eventually turn to God.

Katy, who shares her parents' faith and has a 'Jesus' Tattoo on her wrist, said: "My mum has this idea about Russell that he's going to be a great man of God and his transition is happening.

"I think it is happening in some way, but won't be exactly specific to what my parents think. Can you imagine where he's come from to where he is now?

"There's got to be a reason why he's arrived at all."

US born Katy, who is set to marry Russell next month, also admits the Get Him to The Greek' star's legendary charms have worked on her mother, which she finds "totally inappropriate".

She added to Radio Times magazine: "My parents always give the benefit of the doubt and it's up to the person to mess it up.

"Russell was very charming with them. My mother flirts with him, which I find totally inappropriate, and I tell him to stop."

It has previously been reported how close Katy has become to the British star's mother, Barbara, and that she even calls her "mum".

A source close to the singer said: "She adores Barbara. They're in constant contact and speak on the phone most days.

"They try and see each other as much as possible when they're in the same country. Katy joked that she calls her own mother Mom and Russell's mother Mum."