Kim Kardashian's mother Kris Jenner has turned to police for help amid reports suggesting she has become the target of an extortion plot over a non-existent sex tape.

The reality Tv matriarch claims she has been bombarded with up to 300 phone calls, voice mails and text messages every day for the past few weeks from a person who claims to have obtained explicit footage of Jenner engaged in a steamy romp.

The mystery caller has allegedly demanded the Keeping Up With the Kardashians star pay up in a bid to keep the tape under wraps, prompting Jenner to call in the cops.

Officers from Los Angeles County Sheriff's Department paid a visit to the family home on Tuesday (25Mar14) to take down details about the incidents for a police report, according to Tmz.com.

Jenner is adamant the sex tape does not exist, despite previously confessing to once filming herself and her estranged husband, former Olympian Bruce Jenner, making love early on in their relationship.

The couple separated last year (13) after 22 years of marraige.