In a development which could aggravate already fragile trade relations between United States and China, a report has emerged claiming that China clandestinely fitted surveillance microchips into the servers of US companies including Apple and Amazon, Gadgets 360 has reported.

In the article by Bloomberg, there are claims of years-long effort by the Chinese military to install the surveillance chips in motherboards of the servers of these companies. The motherboards of these servers were assembled in China.

As per the report, the operation to install the surveillance chips into the motherboards was conducted by a Chinese military unit that specialises in hardware. The military unit inserted a tiny, innocuous-looking microchip onto the motherboards of Supermicro which is a leading supplier of such equipment. Supermicro is a US company based in San Jose but its motherboards were mainly assembled in China.

Servers of one such affected company were used by U.S. government clients, including data centres of Department of Defence, Navy warships and the CIA in its drone operations.

However, it was unclear from the report how much data was collected by China using the surveillance chips, the magazine has reported.

According to the report, a top-secret investigation involving the FBI and dating back to 2015 remains open.

China, Apple, Amazon and Supermicro has denied the claims made in the article.

Apple has denied claims made in the report saying that the report was inaccurate and the company has never found malicious, hardware manipulations or vulnerabilities planted on a purpose. It also denied any knowledge of the FBI investigation into the matter and said that the company never had any contact with the FBI.

Amazon Web Services, a subsidiary of Amazon, has also denied the claims in a statement issued. "It's untrue that AWS knew about a supply chain compromise, an issue with malicious chips, or hardware modifications when acquiring Elemental, It's also untrue that AWS knew about servers containing malicious chips or modifications in data centers based in China, or that AWS worked with the FBI to investigate or provide data about malicious hardware."

Supermicro, in a statement said, "We are not aware of any investigation regarding this topic nor have we been contacted by any government agency in this regard."