The US government uncovered a “broad and significant” cyber espionage campaign targeting commercial telecoms infrastructure in the country, allegedly conducted by China-linked hackers.

In a statement, the FBI and the Cybersecurity and Infrastructure Security Agency, which led the probe, claimed China-affiliated actors had “compromised networks at multiple telecommunications companies”.

The breaches enabled the theft of customer call record data, compromised private communications of a limited number of individuals involved in government or political activity, and some information subject to US law enforcement requests had been copied.

“We expect our understanding of these compromise[s] to grow as the investigation continues,” read the statement.

Other potential victims have been alerted and the two agencies stated they are working to strengthen cyber defences across the commercial communications sector.

Impacted companies were not named in the statement, however news outlets reported a month ago a China-linked-group called Salt Typhoon had attacked networks operated by AT&T, Verizon and Lumen.

The hacks reportedly targeted the phones of presidential candidates Donald Trump and Kamala Harris in the run-up to the US election.