On Thursday, Apple Inc and Amazon both denied a Bloomberg report which charged their systems as containing malicious computer chips inserted by Chinese intelligence.

According to Bloomberg Businessweek, 17 unnamed intelligence and company sources stated that Chinese spies are helping Beijing gain secret access to internal networks by placing computer chips inside equipment used by around multiple companies, as well as multiple U.S. government agencies.

According to Bloomberg reports, it seems like a unit of the Chinese People’s Liberation Army infiltrated the supply chain of a hardware company called Supermicro and planted malicious chips. The operation is thought to have been targeting valuable commercial secrets and government networks.

The company was unable to provide an immediate comment, as said by a representative for Supermicro at its European headquarters in the Netherlands.

Beijing’s denial of allegations of orchestrating cyber attacks against Western companies is certainly not a new thing. Moreover, there was no immediate response to a written request for comment by China’s Ministry of Foreign Affairs on Thursday.

The tech companies released separate statements which have been published by Bloomberg.

We’ve found no evidence to support claims of malicious chips or hardware modifications. – Amazon

Apple said it had refuted “virtually every aspect” of Bloomberg’s report, stating that “Apple has never found malicious chips, ‘hardware manipulations’ or vulnerabilities purposely planted in any server.”

Concerns have been on the rise about foreign intelligence agencies, especially Chinese, infiltrating the US and other companies via “supply chain attacks.” In China, multiple global tech firms outsource their manufacturing.

Moreover, on Wednesday came a warning from the US government about hacking group widely known as ‘cloudhopper’ that has been linked to the Chinese government. It is said that Cloudhopper notoriously launched attacks on technology service providers in a campaign to steal data from their clients.

The warning came after prominent US cyber security company experts spoke of a surge in the Chinese hacking activity amid the escalating trade war between Washington and Beijing.