Police in Singapore have issued an alert citing a dramatic rise in the number of "cyber blackmail" cases being reported. But unlike many cases that have been documented before which target women or teenagers, this latest rash of crimes targets men through social media sites.

The Singapore Police Force reports that there have been more than 50 reported cases in the last year where "foreign" women have lured men through invitations on social networks, such as Facebook and Tagged.com, into video sex sessions that are recorded for blackmail purposes.

The women "initiate cybersex" with the men over video chat, stripping for them and then encouraging them to do the same, and then to perform sex acts on camera for them - all the while recording the men's video feed. The victim is then contacted later and threatened with posting of the video in public if they don't wire money to the scammers.

This is the second time this year Singapore authorities have issued an alert regarding this sort of cyber-extortion. In August of 2012, police issued a similar warning after having more than 32 reported cases in the first half of the year; there were 11 reported cases in all of 2011 of similar scams.

The trend in Singapore mirrors an increase in reported cases worldwide where men are blackmailed over cybersex sessions. Last October, for example, extortionists used video of a Quebec businessman to attempt to extort him, even sending the video to the Canadian Broadcasting Company's French-language service in an attempt to pressure him to pay up. Five other men in Quebec and one woman were targeted by the same scammers.

As Sohpos' Graham Cluley points out, the scam may go far beyond simple blackmail. The websites used for some of these chat sessions could be used to spread malware as well - even taking over their webcam when they're not using it.