After Sunday night’s Grammy Awards fans of Britney Spears were calling on Katy Perry to apologise, after she made jokes on the red carpet that appeared to reference when Spears shaved her head in 2007.

But while Perry has stayed quiet, Spears seems to have hit back, by posting a very telling Bible quote on her Twitter account.

On Monday evening Spears tweeted: “Her mouth speaks from that which fills her heart Luke 6:45”, along with a picture of two hands making a heart shape.

While on the Grammys red carpet on Sunday night Perry was asked by presenter Ryan Seacrest about taking a break between albums, to which she replied: “That’s called taking care of your mental health”.

When Seacrest then asked how her time off had gone Perry answered: “Fantastic. And I haven’t shaved my head yet”.

More: Britney Spears Fans Want Katy Perry To Apologise For Head Shaving Jokes At Grammys

Then in another red carpet interview Perry, who has just dyed her hair platinum blonde, appeared to reference Spears again when she said: “It’s like the last colour in the spectrum that I can do,” in reference to her new hair colour.

“I’ve done all of them and the only thing left to do is shave my head, which I’m really saving for a public breakdown,” she added. “I’m down for that. I’m almost moments away from that, obviously.”

Fans of Spears were quite to blast Perry on Twitter and demand an apology. One fan wrote: “@katyperry U should apologize to @britneyspears. Shame on u Katy. She never shades anyone.”

Another added: "Have always liked Katy Perry very much, have even met her. But after what she said last night, I’ve lost a lot of respect for her…Making a joke about mental health issues isnt OK.”