Kaitlynn Carter's co-star Spencer Pratt says her relationship with Miley Cyrus was 'very suspicious'

Spencer Pratt thinks Kaitlynn Carter's relationship with Miley Cyrus was fake. Photo / Instagram.

Spencer Pratt doesn't believe Kaitlynn Carter and Miley Cyrus were dating.

The couple - who split last month - enjoyed a whirlwind romance after they each split from their respective partners, Brody Jenner and Liam Hemsworth, but Kaitlynn's co-star from The Hills: New Beginnings thinks the relationship "seemed very suspicious", and doesn't think it was real.

"So we know they were actually together at one time? Ever? I mean I'm just saying, I don't believe anything … It seemed very suspicious to me," he said.

Spencer, 36, made his comments as he attended the Marriage Boot Camp 100th episode celebration alongside his wife Heidi Montag, where he also revealed he is interested in getting 26-year-old Miley's new beau Cody Simpson on The Hills.

Spencer Pratt doesn't believe Kaitlynn Carter and Miley Cyrus were dating. Photo / Instagram.

When asked by People magazine who he wanted to appear in the next season, Spencer quickly replied: "Definitely Cody Simpson."

The comments come after Spencer also previously stated he'd love to see Miley herself appear on the show.

Meanwhile, Spencer lashed out at 30-year-old Kaitlynn last month, when he accused her of having an "emotional" relationship with the Slide Away hitmaker before she had officially split from Brody in August.

Miley Cyrus and Kaitlynn Carter got together while holidaying in Italy. Photo / Instagram.

He said: "It's tough for me to listen to Kaitlynn complain about people talking about her open relationship with Brody when we know she had a thing going with Miley. She already had something going on with [Miley] when these scenes were filming - maybe not physically, but definitely emotionally. No one's judging you for whatever it is you and Brody do when he's not sleeping in his car. We just don't want people to lie about their lives."

People began speculating that Kaitlynn and Miley were in a relationship in August when they were spotted locking lips on a yacht a few days after the Malibu singer confirmed that she and her husband Liam Hemsworth had gone their separate ways.

Miley Cyrus is now dating Cody Simpson. Photo / Instagram.

An insider said at the time: "Miley is very close with Kaitlynn. It's romantic, but also a friendship. They are both going through similar stuff right now and are bonding over it."