The US Defence Department temporarily cut off public access to most of its Web sites on Monday to ensure that they are protected against the "Code Red" computer virus, some versions of which display the slogan "Hacked by Chinese!" on infected Internet sites.
"Most DoD (Department of Defence) Web sites will not be accessible by the public until this worm no longer poses any threat to DoD networks," said Lt. Col. Catherine Abbott, a Pentagon spokeswoman.
Technicians are working to determine whether security patches needed to fix the problem previously had been installed, Abbott said.
"To protect the DoD Web sites from being compromised, DoD organisations have been directed to review the status of their Internet information servers to ensure that the appropriate patches were previously installed," she said.
The "Code Red" virus, which is technically a self-propagating worm, first surfaced last week, according to Marc Maiffret, chief hacking officer at security software company eEye Digital Security.
"Since then, at least 300,000 sites have been infected, including a large number of US government and US military Web servers," Maiffret said.
Code Red is programmed to start replicating itself on the first day of the month, so it could start spreading again next month, Maiffret said.
The White House last week averted a planned "Code Red" attack on its Web site, the home page for the Bush administration, security experts said.
