https://www.bbc.com/news/technology-45747983
Apple and Amazon are among US companies and agencies who have had data stolen by Chinese spies, claims Bloomberg.
The data had been siphoned off via tiny chips inserted on server circuit boards made by a company called Super Micro Computer, reported the news agency.
The servers had been compromised during manufacturing and the chips activated once they were up and running, it said.
Apple, Amazon and Super Micro have rejected Bloomberg's claims, calling them "untrue".
In particular, Apple released a strong statement in response to Bloomberg's article saying it had found "no evidence" to support the allegations.
Bloomberg said a year-long investigation by reporters Jordan Robertson and Michael Riley had uncovered evidence of the wide-ranging attack, which gave Beijing access to 30 large companies and many federal agencies.
t said the first information about the spying campaign had emerged during security testing carried out by Amazon in 2015 before it had started using servers from US company Elemental, which had been manufactured by Super Micro Computer at plants in China.
And this discovery then kicked off a long-running "top-secret probe" by US intelligence agencies, which found compromised servers:
in Department of Defense data centres
onboard warships
handling data gathered by CIA drones
China was well placed to carry out this kind of attack, said Bloomberg, because 90% of the world's PCs are made in the country.
Carrying out the attack involved "developing a deep understanding of a product's design, manipulating components at the factory, and ensuring that the doctored devices made it through the global logistics chain to the desired location", it said.