Security experts issued a warning today about a newly intercepted spyware program called DigiKeyGen, which purports to give free access to pornographic web content, but in fact blackmails unwitting users who have downloaded it.

The program is found on a web page that allows visitors to download a password generator in order to gain free access to pay-per-view "adult resources ".

When users run DigiKeyGen, they receive passwords that supposedly allow them access to pornographic websites.

At the same time, a spyware program and an alleged anti-spyware application are installed on the computer without the user's knowledge.

It then warns the unwitting user that their computers are infected and offers them an anti-spyware program to clean the system for $49.95.

Panda Software Labs has discovered that DigiKeyGen can be downloaded from other websites offering adult content in addition to the program's official page.

Luis Corrons, director of Panda Software Labs, said: "You must always be suspicious of offers for something in exchange for almost nothing.

"Cyber-crime simply applies traditional fraud techniques to the internet and anybody tempted by the chance to get something for nothing is taken in, unaware of the risks of apparently harmless actions such as downloading small programs or accessing certain websites."

The technique used in this case is not new. Other alleged anti-spyware programs detected in the past, such as RazeSpyware or SpySheriff, also had the same lure as DigiKeyGen, offering to clean nonexistent spyware, or spyware installed with user consent, for a modest fee.

"Even users with sound IT knowledge could drop their guard with offers like this," explained Corrons.

"It is essential to be cautious of irresistible offers on the internet. Users should leave the task of deciding whether or not a program is malicious to an anti-malware solution."