Jim McAuley knows all about the dangers of the site.

A former adult instructor in the Lancashire Army Cadet Force, McAuley, from Chorley, resigned from his role after posting a series of claims on the social networking site about his supposed military past.

Claiming to be a battle hardened war hero - a former 2 Para and SAS soldier who killed more than 100 men - the Evening Post revealed he used the site to spin a series of elaborate tales about his past - before serving troops posing as a woman caught him out.

He has refused to speak about the incident, but what is clear is Mr McAuley is just the latest in a long line of people who have found out the hard way about the astonishing hidden dangers of an astonishingly popular website.

Facebook has more than 30 million users the world over and 3.2 million in Britain.

For most it is a useful tool to spark up old friendships, keep in touch with friends and, for some, a 21st century way of meeting new people.

But social networking sites like Facebook have also left users wide open to a new wave of fraud, corruption and other emerging problems.

Among the latest victims could be the police.

One of Lancashire's most senior officers has spoken out to warn of growing fears networking sites could be used to corrupt police officers.

Mike Cunningham, the Association of Chief Police Officers lead officer on counter-corruption and Deputy Chief Cons of Lancashire Constabulary, warns police need more guidance on using the sites to protect them from villains.

He told industry magazine Jane's Police Review: "If I put out (on the internet] the fact that I am Mike Cunningham, I am a police officer and these are my hobbies, then we know there are people out there that are actively seeking to corrupt.

"We do not know the scale of it but we do know there is the potential for it to become a problem for the service."

The police, of course, are not the only group where problems have been flagged up.

Last year the University of Central Lancashire sounded a serious warning about the dangers of revealing all on the sites after bringing a number of disciplinary actions against students for serious "breaches of confidentiality" on sites like Facebook, My Space and Bebo.

Meanwhile, many employers have now banned their use at work, while employees have found themselves sacked because of comments made about colleagues or their workplace - or even because they have updated their profile to suggest they are actively looking for work.

Of course, many of these problems are avoidable if people simply adjust their privacy settings to control what people can see. But many do not.

Nigel Evans, a member of the Commons culture, media and sport committee, which has discussed this said people should always err on the side of caution.

"It is fraught with dangers so if you are going to enter these sites you should be totally honest about yourself and everything you are going to put there," he explains.

"The much wider area though is that you have to remember if your privacy settings are not quite right you are sharing information with people you just do not know."

Even Facebook itself urges users to ensure they take full advantage of the site's privacy settings.

"Facebook aspires to be an environment where people can interact safely with their friends and the people around them. We have implemented many safety and privacy controls on Facebook as part of our goal to enable people to share their information with only the people they want to see it," says a statement on its user 'safety' pages.

"And we are constantly improving our systems for identifying and removing inappropriate content and people from the site."