Computer hackers have warned that a week-long national holiday in China from Friday could leave the country vulnerable to further attack from a potentially lethal computer virus.
The Stuxnet cyberworm, dubbed the world's "first cyber superweapon" by experts and which may have been designed to attack Iran's nuclear facilities, has already hit millions of computers around the country.
Stuxnet is feared by experts around the globe as it can break into computers that control machinery at the heart of industry, allowing an attacker to assume control of critical systems like pumps, motors, alarms and valves.
It could, technically, make factory boilers explode, destroy gas pipelines or even cause a nuclear plant to malfunction.
China's biggest hacker group told the South China Morning Post on Friday that cybersecurity staffing at large state-owned enterprises would be minimal during the holiday to mark the founding of the People's Republic of China.
"China's industrial networks become incredibly weak and therefore much easier to infiltrate during the national holiday, because everybody is off," a spokesman for the Chinese Honker Union told the paper.
"So if they are up to something they may very likely do it now."
Stuxnet is believed to target control systems made by German industrial giant Siemens commonly used to manage water supplies, oil rigs, power plants and other industrial facilities.
The computer worm - a piece of malicious software (malware) which copies itself and sends itself on to other computers in a network - was first spotted by Siemens on July 15, a company spokesman told AFP.
There are also concerns that the holiday could slow any Chinese government response.