By David Shepardson

WASHINGTON (Reuters) – U.S. government authorities will hold a classified briefing for all senators on Wednesday about China’s alleged efforts dubbed “Salt Typhoon” to penetrate deep into American telecommunications companies and steal data about U.S. calls, according to officials and a statement seen by Reuters .

The FBI, Director of National Intelligence Avril Haines, Federal Communications Commission Chairwoman Jessica Rosenworcel, the National Security Council and the Cybersecurity and Infrastructure Security Agency are expected to attend the briefing at 3 p.m. ET, the officials said.

Separately, a U.S. Senate commerce subcommittee plans to hold a hearing on the Salt Typhoon hacking attack on Dec. 11, officials said.

The briefing comes amid growing concerns about the scale and scope of reported Chinese hacking into U.S. telecommunications networks and questions about when companies and the government can reassure Americans on the matter.

The White House did not immediately comment. U.S. officials have previously claimed that the hackers targeted Verizon, AT&T, T-Mobile and others, stealing phone audio recordings and a large tranche of call recording data.

Chinese officials had previously called the allegations disinformation and said Beijing “strongly opposes and combats cyberattacks and cybertheft in all forms.”

CISA told reporters on Tuesday that it could not provide a timeline for eliminating all hackers in America’s telecommunications networks.

“It would be impossible for us to predict when the full evacuation will occur,” said CISA official Jeff Greene.

(Reporting by David Shepardson; Editing by Jason Neely)