Two US government sites were hacked late last week by a group calling themselves "mujihadeens".

The hackers defaced the home page of the NOAA Office of Performance Computing and Communications and a page operated by the National Human Genome Research Institute, according to US reports.

The pages were defaced with the flag of Saudi Arabia and a message in Urdu which translates as: "Allah is the greatest of all... Americans be prepared to die."

The attackers called themselves "mujihadeens" and threatened further cyberterrorism.