Kim Kardashian confessed to an embarrassing secret when she was interviewed by supermodel Cara Delevingne - she once soiled herself while wearing curve-boosting underwear.

The reality Tv star sat down for a heart-to-heart chat with the British beauty after Delevingne signed up as guest editor for the new edition of Love magazine.

However, the catwalk queen stunned her subject by asking brutally direct questions, and Kardashian gamely joined in and gave honest answers.

The publication's editor-in-chief Katie Grand tells Britain's The Sunday Times Style magazine, "Cara asked Kim if she's ever wet herself in a pair of Spanx. Kim says yes. If anyone else had asked Kim that, she'd probably have punched her. Cara is adorable and infectious, and you like being around her. She's funny and cute. So, when she asks really intrusive questions, she gets away with it."

Delevingne adds, "I was honest and asked direct questions, and if that makes a good interview, then I think I did Ok."