Chinese hackers have targeted mobile phones used by Republican presidential nominee Donald Trump and his running mate JD Vance as well as people associated with the Democratic campaign of Kamala Harris, sources have said.

An FBI statement did not confirm that Mr Trump and Mr Vance were among the potential targets but said it was investigating “unauthorised access to commercial telecommunications infrastructure by actors affiliated with the People’s Republic of China”.

“Agencies across the US Government are collaborating to aggressively mitigate this threat and are coordinating with our industry partners to strengthen cyber defences across the commercial communications sector,” the FBI said.

Republican vice presidential nominee JD Vance
Republican vice presidential nominee JD Vance (Paul Sancya/AP)

US officials believe the Republican pair are among several people whose phone numbers have been targeted and suspect it to be part of a larger cyber-espionage campaign launched by China.

The New York Times first reported that Mr Trump and Mr Vance had been targeted and said the campaign was alerted by US officials this week.

The FBI has repeatedly warned over the last year about Chinese hacking operations, with FBI director Chris Wray telling Congress in January that investigators had disrupted a state-sponsored group known as Volt Typhoon.

That operation targeted US-based small office and home routers owned by private citizens and companies. Their ultimate targets included water treatment plants, the electrical grid and transportation systems across the US.

Last month, Mr Wray said that the FBI had interrupted a separate Chinese government campaign that targeted universities, government agencies and other organisations and that installed malicious software on more than 200,000 consumer devices, including cameras, video recorders and home and office routers.

A spokesperson for the Chinese embassy in Washington said they were not familiar with the specifics and could not comment, but contended that China is routinely victimised by cyber attacks and opposes the activity.

“The presidential elections are the United States’ domestic affairs. China has no intention and will not interfere in the US election. We hope that the US side will not make accusations against China in the election,” the statement said.

Trump campaign spokesman Steven Cheung did not offer any details about the Chinese operation but issued a statement accusing the Harris campaign of having emboldened foreign adversaries, including China and Iran.

The Wall Street Journal reported this month that Chinese hackers had burrowed inside the networks of US broadband providers and had potentially accessed systems that law enforcement officials use for wiretapping requests.