Caroline Flack has alerted the police after reportedly receiving a threatening photo on Twitter.

The Xtra Factor has been subject to a series of abuse on the social networking website after she dated One Direction heartthrob Harry Styles last year.

Their relationship was criticised for its 15 year age gap before it ended some months later.

Flack yesterday (July 19) sent a tweet to London's Metropolitan Police force with a photo she had received from a female who was holding a knife.

She simply said to the police: "Acceptable tweet?"

As previously reported, Flack earlier this year opened up on her relationship with Styles, admitting that she has learnt a "difficult lesson" as a result of all the media furore.