Katy Perry documents her break-up in concert film

Katy Perry says it was important to leave "difficult" parts of her life in her new 3D concert documentary, including her recent divorce.

The film, Katy Perry: Part of Me, follows the pop star on her world tour amid her break-up with ex-husband Russell Brand.

The singer said over 300 hours of footage was gathered from her year-long world tour for the film.