Billie Eilish has revealed she and her brother Finneas have started writing songs for her next album.

During her sixth annual time capsule interview with Vanity Fair, the 20-year-old singer revealed that she and her songwriting partner were working on her third studio album and the follow-up to 2021's Happier Than Ever.

"We see each other all the time, and also now, we're starting to make music again," she said of her brother. "We just started the process of making an album, which is really exciting so now we have specific days where we see each other, which is really nice because, you know, you get caught up in life. I'm hanging out with my brother a lot actually. It's my buddy!"

During a quickfire Q&A segment using fan-submitted questions, Billie said they are currently working on one track.

Elsewhere, the Bad Guy singer noted her least favourite song in her back catalogue is Watch, from her 2017 EP Don't Smile at Me, and urged her fans to have faith in her decisions.

"Trust me. I'm in control, I'm in charge, I know what I'm doing, I'm O.K., you can trust me, I'm not going anywhere," she insisted.

Billie also shut down speculation that she has joined the third season of HBO teen drama Euphoria, which stars Zendaya.

"That's not true. I'd like to be, Euphoria is f**king fire," she added.

The singer has sat down for the same interview with Vanity Fair on 18 October every year since 2017. She announced on Monday night that she will release them every few years going forward.