The Chinese effort to hack prominent Americans is far more widespread than previously reported, ABC News has learned.

Sources told ABC News that U.S. law enforcement and intelligence officials are concerned that the Chinese government’s spying operation may have been going on for over a year — and possibly longer — before it was recently discovered .

The Chinese appear to have been able to collect large volumes of data in a sweeping covert campaign targeting the cellphones and mobile devices of business leaders and other high-profile Americans from both political parties, according to sources familiar with the investigation.

Evidence is mounting that, in some cases, the Chinese operation was able to access or have access to cellphone users in Verizon, AT&T and Lumen were communicating.

Authorities are trying to determine whether the Chinese were able to listen to the conversations and view text messages in real time as they took place, or whether they captured the footage for later review.

Sources said US officials are just beginning to understand the extent of the Chinese operation, but what they have discovered so far is deeply troubling and represents a massive breach of privacy on a disturbing scale.

MORE | Trump’s top lawyer’s cellphone was compromised by Chinese hackers, sources say

Targets included not only former President Donald Trump and Senator JD Vance, but also individuals working in a number of government agencies.

The FBI is systematically contacting victims, sources said.

Salt Typhoon, the name given to an advanced and persistent threat actor led by the Chinese government, is believed to be behind the operation.

Intelligence officials suspect the Salt Typhoon hackers exploited the routers as a gateway to cellphones and mobile devices, and there are concerns that Chinese intrusion capabilities may have made significant advances.

In a statement issued last month, Verizon representatives said: “We are aware that a highly sophisticated state actor has targeted multiple US telecommunications providers to collect information. Along with federal law enforcement, industry peers and third-party cyber experts, we were and are working to confirm, assess and remediate any potential impact. Verizon is committed to assisting law enforcement in this investigation.”

Representatives for AT&T and Lumen declined to comment

According to sources, the FBI has determined that Blanche’s communications with family and friends were compromised, and investigators are still trying to determine whether communications with more sensitive contacts were affected.

Sources told ABC News that Blanche may become Trump’s next White House adviser or take a leadership role in law enforcement under a new Trump administration.

China’s sweeping hacking operation made national headlines two weeks ago when the FBI issued a statement saying it was investigating newly identified “malicious activity” by “actors affiliated with the Chinese government” targeting commercial telecommunications infrastructure.

The statement said the FBI and the Department of Homeland Security’s Cybersecurity and Infrastructure Security Agency notified victims of the operation. These reportedly included private companies and individuals, who later strengthened their security measures and replaced the compromised cellphones, according to the sources.

ABC News previously reported that Trump and his running mate, Sen. JD Vance, were told last month that they and others associated with the campaign were among the victims whose cell phones were targeted. Democrats were also targeted, ABC News said.

The FBI believes the hackers were unable to access encrypted apps on the phones they targeted, but the investigation continues to confirm that and identify other victims, according to sources.

Earlier this week, the Wall Street Journal reported that hackers linked to Chinese intelligence services compromised phone lines used by politicians and senior national security and policy officials in the US government, allowing the hackers to “collect call logs, unencrypted texts and some sound from potentially thousands of Americans and others they interacted with.”

Asked about the latest reports from ABC News, an FBI spokesman declined to comment.

Steven Cheung, Trump’s spokesman, said in a statement: “Make no mistake, foreign adversaries are horrified by President Trump’s strength and resolve. President Trump will stand up to our enemies and defend the United States from any aggression. He will not let anything stop him or get in his way of fighting for the American people and making America great again.”

Blanche oversaw Trump’s defense in the former president’s weeks-long criminal trial in New York, where a jury in May convicted Trump of 34 counts of criminal fraud stemming from his role in falsifying business records to hide cash payments to adult film star Stormy Daniels to boost her electoral prospects in the 2016 presidential election.

Sentencing is set for later this month, though it’s unclear if that will still happen after Trump was re-elected to the White House on Tuesday.

After Trump’s sentencing in May, Blanche told The Associated Press that Trump “knows there’s a lot of fighting left and there’s a lot of opportunity to fix this, and that’s what we’re going to try to do.”