Hackers linked to Communist China have accessed audio of phone calls and text messages from American “political figures,” according to a report from the Washington Post. The breach is believed to have been carried out by the China-linked group known as Salt Typhoon, the Post reports.

In an espionage operation that officials believe began months ago, the hackers were able to access information from phone calls of American “political figures,” including an adviser to President Trump’s campaign. 

However, officials tell the Post that they believe the number of people targeted in this breach was fewer than 100. A former intelligence official explained to the paper that the hackers could have seen the ability to access such information as an “exquisite” opportunity and declined to try to target more individuals out of fear of being detected.

The FBI declined to comment on the audio collection report. 

Last week, multiple reports said hackers, believed to be part of the same group, targeted the phones of Trump, Senator Vance, and members of Vice President Harris’s campaign. It was unclear what information was recovered from the phones. 

Officials told the Wall Street Journal they believe the hackers were able to access the phones through a breach of telecommunications infrastructure.

Earlier this month, the Journal and CNN reported that Salt Typhoon hackers accessed wiretap warrant requests during a breach of telecommunications such as Verizon, AT&T, and Lumen.

Telecommunications companies hold vast amounts of data on callers that law enforcement officials can request access to with a warrant. That data could give Beijing information about who American law enforcement officials are investigating and provide opportunities to undermine intelligence operations.

As with previous intrusions, Communist China’s foreign ministry denied any knowledge of the hack and claimed American officials had “concocted a false narrative.”

“At a time when cybersecurity has become a common challenge for all countries around the world, this erroneous approach will only hinder the efforts of the international community to jointly address the challenge through dialogue and cooperation,” the foreign ministry told Reuters.

Last week, American officials publicly acknowledged that breach for the first time, as the FBI said it was investigating “unauthorized access to commercial telecommunications infrastructure.”