The US marine corps have become the latest branch of the American military to ban the use of social networking sites, after officials expressed concern about potential security risks.

An order sent out to marines yesterday informed them that they could no longer use sites including Facebook, MySpace and Twitter in case enemy groups used the information they contained to their advantage.

"These internet sites in general are a proven haven for malicious actors and content, and are particularly high risk due to information exposure, user-generated content and targeting by adversaries," said the order. "The very nature of social networking sites creates a larger attack and exploitation window."

Coming just days after US deputy defence secretary William Lynn ordered a review of the military's social networking policies, the move is being seen by some as a signal that the Pentagon could enact a blanket ban on social networks across the entire military system.

Lynn's review, which is due to be completed by the end of August, plans to weigh up the benefits and drawbacks of allowing members of the army, navy and air force to use social media.

Officials recognise that thousands of active personnel use sites like Facebook to keep in touch with friends and family at home, sharing information and swapping photos while on long tours of duty. But the benefits of such freedom are often contrasted with grave concerns over the possibility of classified information leaking out.

As a result, the order from the marines is not the first time they have brought the curtain down on certain aspects of internet use.

In 2007 the Pentagon blocked its computer networks from accessing sites including YouTube and MySpace in an attempt to keep a tight rein on information about troop activities. Official documents at the time cited not only threats to safety, but also the increasingly heavy burden being placed on the department's internet capability while troops were active duty in such as Iraq and Afghanistan.

Although that ban was eventually lifted, last year the Pentagon used a fresh tactic to try and control the flow of information by launching TroopTube - a military-sponsored version of YouTube that allows serving personnel to share videos with only their friends and family members. All videos placed on the site must be checked by a Department of Defense worker before they are approved.

At the same time, the military has discovered the benefits of using the social web to its advantage. The Pentagon recently launched its own Facebook page in an attempt to entice new recruits into the military, while Admiral Mike Mullen - who serves as chairman of the joint chiefs of staff, the highest-ranking military officer in the US - is an avowed Twitter user with more than 4,000 followers.

Some personnel will be allowed to continue using social networking sites, but only with a waiver from higher-ranking officers or in "mission critical" circumstances.