According to the Federal Bureau of Investigation, an increased number of incidents of hijacked social networking accounts have been reported to the agency.

The FBI put out a release today warning users of Twitter, Facebook, MySpace, and similar sites to beware for a common hacking scheme that is becoming more frequent.

One of the more popular methods of hijacking involves the use of spam e-mail sent from a previously hijacked account. Opening the e-mail allows the hacker to access the user's passwords, then send other spam messages to the user's online friends. The messages entice recipients to open them by saying the sender is in medical or legal trouble.

The incidents have been reported to the Internet Crime Complaint Center (IC3), a joint venture between the FBI, National White Collar Crime Center, and the Bureau of Justice Assistance.

The release said that the sites are still "generally a safe place to interact with friends," but urged users to be cautious of such schemes.

The IC3 has received 3,200 reports of hijackings since 2006, according to the release.

No incidents are known to have involved members of Congress.