Katy Perry says one in all her greatest regrets is popping down a Billie Eilish collaboration.

The 38-year-old singer revealed she was approached about working with Billie, 21, earlier than she turned an enormous star however Katy turned down the supply.

In a TikTok posted by 102.7 KIIS FM, Katy may be seen explaining: “Someone sent me an email one time that was: ‘Hey, check out this new artist. I’d really like us to work with her because she was working with me for Unsub [Records].

“It was a music known as ‘Ocean Eyes,’ and it was only a blonde lady. And I used to be like, ‘Meh, boring.’

“Big mistake. Huge mistake. Don’t let this hit the Internet.”

Eilish went on to search out fame in 2015 with ‘Ocean Eyes’ and has since received seven Grammy Awards and a Golden Globe Award and Oscar for Best Original Song.

Katy appeared in Billie’s 2021 documentary, ‘Billie Eilish: The World’s A Little Blurry’, when she revealed her associate Orlando Bloom was an enormous fan.

Katy advised Billie: “My fiancé who doesn’t listen to modern music, he’ll only play you in the car all the time.”

She added: “Congrats, I’m so proud of you. I wanted to say, this is going to be wild for 10 years. If you ever wanna talk… ’cause it’s a weird ride.”