DETECTIVES have warned internet users to be on their guard after three men were blackmailed over social media by a woman.

The woman, who claimed to be called Cathy Wong, befriended the men, who are all students in York, on Facebook and asked them to video call her using skype.

She enticed them into performing an indecent act which she recorded on video before telling the men her grandmother was ill and needed to send her £3,000 by money transfer.

A North Yorkshire Police spokeswoman said when the men refused to send the money, she threatened to upload the video to Youtube.

Officers are investigating whether the scam is being operated by an organised crime group.

Detective Sergeant Rebecca Dyer said: “This scam is causing considerable distress to the victims and I urge anyone who uses any kind of social networking site to be very wary of what they are getting into.

“I am concerned that there are other victims of this scam who are too embarrassed to come forward about what has happened.

"Please do not suffer in silence, get in touch with the police.

"Your information will be dealt with in the strictest confidence and with sensitivity."

To report an incident, call police 101 or email Rebecca.dyer@northyorkshire.pnn.police.uk