AceShowbiz -

Heidi Montag's partner in girl-on-girl sex tape, Playboy Playmate Karissa Shannon, has confirmed that she and the "The Hills" star once filmed such explicit video. While promoting her new signature milkshake at Millions of Milkshakes in West Hollywood on Thursday, August 26, Karissa told Radar Online, "There is a sex tape of me and Heidi."

"It's just me and Heidi, that's it," Karissa later stressed that Heidi's estranged husband Spencer Pratt was not involved in the filming of footage. The blonde, who at that time was accompanied by boyfriend Sam Jones III, went on saying that Spencer didn't know about the tape and claiming he has stolen her video camera containing the footage.

"Me and Heidi were hanging out at her house in Malibu and he came over to pick up some stuff and he 'accidentally' took my camera," Karissa said. "I talk to Heidi every single day and I tried to be there for her when she was going through her divorce, but now it's starting to affect my life."

"Spencer had no right to steal my camera. There are other things on there that I don't want to come out, including the video of me and Heidi," Karissa continued, before adding that she doesn't "want people to see it." Now that the sex tape might soon become a public consumption, Karissa mused, "I don't know, I just wish I'd done it [the sex tape] with Lindsay Lohan. At least it wouldn't be on the market right now!"

Karissa Shannon on Her Girl-On-Girl Sex Tape With Heidi Montag: