A Chinese-made microprocessor used extensively by the U.S. military has a "backdoor" that allows the chip to be reprogrammed, British researchers allege.

The claim by researchers at Cambridge University comes as U.S. lawmakers express concern about the use of Chinese manufactured electronic components in U.S. military hardware.

If the British researchers are accurate in their claim, the Chinese military could potentially exploit the backdoor to reprogram U.S. infrastructure and various weapons systems, TG Daily reported Tuesday.

The chip can't be patched with a software update to close the backdoor, as the vulnerability is hardware-based, the researchers said.

"Our aim was to perform advanced code breaking and to see if there were any unexpected features on the (U.S. Military) chip. We scanned the silicon chip in an affordable time and found a previously unknown backdoor inserted by the manufacturer. This backdoor has a key, which we were able to extract," Sergei Skorobogatov of Quo Vadis Labs at Cambridge University said.

"If you use this key you can disable the chip or reprogram it at will, even if locked by the user with their own key. This particular chip is prevalent in many systems from weapons, nuclear power plants to public transport," he said. "The scale and range of possible attacks has huge implications for National Security and public infrastructure."

Researchers said hackers would need a physical connection between their equipment and the chip and its system to initiate a reprogramming cycle so a cyberattack from a remote location would not be possible.