'Shameful and disgusting': The No1 song which has sparked outrage - from the singer's own parents

The singer’s parents, you might have imagined, would be bursting with pride and rushing to congratulate the 23-year-old on her achievement.

But instead they have launched a ferocious attack on their daughter, and branded the controversial lyric of her song – about two girls kissing – ‘shameful and disgusting’.

Katy's Kiss: She's riding high on the success of her No 1 single...but her religious parents are horrified by its saucy content

Katy’s parents, both evangelical Christian preachers, say they are deeply ashamed of the star for ‘promoting a sin’. And her mother, Mary Hudson, declared: ‘I hate the song. It clearly promotes homosexuality and its message is shameful and disgusting.

‘Katy knows how I feel. We are a very outspoken family and she knows how disappointed her father and I are. I can’t even listen to that song. The first time I heard it I was in total shock. When it comes on the radio I bow my head and pray.’

Ashamed: Katy's mother says she prays every time she hears her daughter's song

Katy appears in the video for the hit in revealing lingerie and posing provocatively, surrounded by writhing models, as she sings ‘I kissed a girl and I liked it / The taste of her cherry chapstick’.

Just over a week ago she leapt into the crowd at a gig and kissed a 16-year-old lesbian fan. But Mrs Hudson claims her daughter, who grew up singing in church, has been led astray by the music industry.

She said: ‘Katy is our daughter and we love her but we strongly disagree with how she is conducting herself at the moment.

'We cannot cut her out of our lives as she is our child but she knows we disagree strongly with what she is doing and the message she is promoting regarding homosexuality which the Bible clearly states is a sin.

'But the Bible also promotes understanding and forgiveness, which I keep reminding myself.

‘Katy is not a homosexual but I fear she has been led astray by the Hollywood crowd. I pray all the time that God will work through her and help her find salvation.’

Of Katy’s outfits, her mother said: ‘Some are too revealing and her father has had words with her about it. Like any child she is going through a period of rebellion.’

Devout: Katy's strict evangelical father Keith Hudson

Katy uses her mother’s maiden name on stage. Her father Keith Hudson calls himself a ‘prophet/evangelist’ and claims to be used by the Holy Spirit to heal people. He travels America and Europe trying to ‘save people’. Katy toured America with her family before they settled in California when she was 11.

Mrs Hudson said: ‘Katy was raised in a very strict Christian household. She started performing in church at nine. She was a special child, she loved to sing and had an angelic voice. That is why this is all so disappointing and sad.

'I think she acts and says certain things to be provocative and to shock.’

Despite the lyrics, Katy had insisted she had never kissed a girl – until she puckered up with fan Jenna Buhmann at her concert in Washington state.

Her first bid for fame was an album of Christian songs in 2001 as Katy Hudson, which hardly sold.

Her mother said: ‘Katy was spotted by a music producer who invited her to LA. That’s when she started to change.

'I was worried she’d start doing drugs and drinking alcohol. I still am. I spoke to her only recently. She said, “Oh Mum, I’m not going to turn into Amy Winehouse”.’

Katy has acknowledged the rift with her parents, saying: ‘I stopped trying to change them at 21.’