Chinese hackers who tapped into Verizon's system were targeting phones used by Republican presidential candidate Donald Trump and his running mate JD Vance, the New York Times reported, citing people familiar with the matter.
The newspaper said investigators were working to determine what communications, if any, were taken.
The Trump campaign was made aware this week that Trump and Vance were among a number of people inside and outside of government whose phone numbers were targeted through the infiltration of Verizon phone systems, it added.
The campaign did not confirm that Trump's and Vance's phones were targeted. Steven Cheung, the campaign's communications director, said the former president's Democratic rival Vice President Kamala Harris has emboldened China and Iran to attack US infrastructure to prevent Trump from returning to office.
The Harris campaign could not be immediately reached for comment.
The Trump campaign was hacked earlier this year. The US Justice Department charged three members of Iran's Revolutionary Guard Corps with the hack, accusing them of trying to disrupt the 5 November election.
The FBI and the US Cybersecurity and Infrastructure Security Agency said on Saturday they were investigating unauthorized access to commercial telecommunications infrastructure by people associated with China. The joint statement by the agencies did not name the targets of the incident.
Verizon said it was aware of a sophisticated attempt to reportedly target US telecoms and gather intelligence.
The largest US telecom company added it was working with law enforcement.
- Reuters