US officials believe Chinese hackers breached at least eight US telecommunications providers in their quest to spy on top US political figures as part of a hacking campaign that has affected dozens of countries worldwide, a White House official said Wednesday.

“Right now, we do not believe any have fully removed the Chinese actors from these networks … so there is a risk of ongoing compromises to communications,” Anne Neuberger, deputy national security adviser, told reporters.

It’s the highest public tally yet the Biden administration has given of the scope of a hacking campaign that has rattled the US national security establishment and is poised to challenge the incoming Trump administration. Officials do not believe the hackers accessed classified information, Neuberger said.

Neuberger’s remarks came as senior US intelligence officials gave a classified briefing to senators Wednesday on the Chinese hacking campaign.

The alleged Chinese hackers have gone after the phone communications of senior US political figures such as President-elect Donald Trump and Vice President-elect JD Vance, as well as senior members of the Biden administration, CNN has previously reported.

China has denied involvement.

US officials are still trying to help major telecom providers evict Chinese government-backed hackers from their networks and don’t have a timeline for when that will be done, officials said Tuesday.

The telecom companies that have worked the longest with federal officials are the furthest along in evicting the hackers, FBI and CISA officials said. Verizon and AT&T are among the major telecom carriers targeted by the hackers, CNN previously reported.

The FBI began investigating the Chinese hacking activity in late spring or early summer this year, a senior FBI official said in the most detailed update yet from the bureau on the espionage campaign.

The hackers stole “a large amount” of bulk phone records that indicate where, when and who people were communicating with, but not the content of the calls or texts, the senior FBI official said. For a “limited number” of people in the US government or involved in politics, the hackers were able to intercept call and text data, the official added.

The hackers also “copied certain information that was subject to US law enforcement requests pursuant to court orders,” the senior FBI official said. But the portal within telecom providers that allows law enforcement agencies to conduct court-ordered wiretaps was not the primary focus of the hackers, the official said.