A state-sponsored Chinese hacking group has been spying on a wide range of US critical infrastructure organizations. It was not immediately clear how many organizations were affected, but the U.S. National Security Agency (NSA) said it was working with partners including Canada, New Zealand, Australia, and the UK, as well as the U.S. Federal Bureau of Investigation to identify breaches.

A state-sponsored Chinese hacking group has been spying on a wide range of U.S. critical infrastructure organizations, from telecommunications to transportation hubs, Western intelligence agencies and Microsoft said on Wednesday.

The espionage has also targeted the U.S. island territory of Guam, home to strategically important American military bases, Microsoft said in a report, adding that "mitigating this attack could be challenging."

While China and the United States routinely spy on each other, analysts say this is one of the largest known Chinese cyber-espionage campaigns against American critical infrastructure.

Chinese foreign ministry spokesperson Mao Ning said on Thursday the hacking allegations were a "collective disinformation campaign" from the Five Eyes countries, a reference to the intelligence sharing grouping of countries made up of the United States, Canada, New Zealand, Australia and the UK.

Mao said the campaign was launched by the U.S. for geopolitical reasons and that the report from Microsoft analysts showed that the U.S. government was expanding its channels of disinformation beyond government agencies.

"But no matter what varied methods are used, none of this can change the fact that the United States is the empire of hacking," she told a regular press briefing in Beijing.

It was not immediately clear how many organizations were affected, but the U.S. National Security Agency (NSA) said it was working with partners including Canada, New Zealand, Australia, and the UK, as well as the U.S. Federal Bureau of Investigation to identify breaches. Canada, UK, Australia and New Zealand warned they could be targeted by the hackers too.