The website of phpBB, an open source bulletin board system, was defaced this weekend by a group of politically motivated hackers, according to a member of the phpbBB development team.

A message was posted by the hackers on the site that contained a picture of US President George Bush on the body of a monkey wearing a diaper.

Individuals close to the phpBB team have speculated the problem may be due to a security flaw in AWStats, a 3rd party visitor statistics program.

The incident appears to have been carried about by the Siemens Crew, according posts on a popular web hosting forum.

The phpBB sever was taken offline Sunday, but the development board (http://area51.phpbb.com) remained active. PHPBB.com has since come back online.

In addition, a support IRC channel remains operational for urgent support requests at irc.freenode.net.

Developers at phpBB insist the security problem is not related to the phpBB software.

"I will take this opportunity to note that given currently available information this hacking episode was not due to phpBB itself. Instead it appears to be due to a third party application," wrote psoTFX of the phpBB group.

Other sites have faced similar problems, according to the message.

"Several other sites were attacked at the same time as www.phpbb.com by the same group displaying the same information and in these cases the same third party application has been blamed (thus far). Equally we are not aware of any other phpBB boards being attacked," said psoTFX.