A judge has sentenced a British man to at least 33 years in prison for murdering and dismembering his teenage stepsister.

Nathan Matthews' girlfriend and accomplice, Shauna Hoare, was sentenced to 17 years in prison for manslaughter for her role in the killing.

The victim was 16-year-old Becky Watts. Matthews, 28, and Hoare, 21, used a circular saw to dismember her body.

Judge James Dingeman, presiding at Bristol Crown Court, said he was certain the planned kidnapping that ended with her death had been intended for sexual purposes.