Phone records associated with the former US president Donald Trump and his running mate, Ohio Senator JD Vancewas targeted in a cyber espionage operation orchestrated by Chinese hackers as part of an intelligence-gathering effort, a US newspaper reported on Friday, citing sources familiar with the matter.

Investigators are assessing whether communications data was accessed or monitored by “breaching sophisticated telecommunications systems,” according to sources who spoke on condition of anonymity because of the sensitive nature of the national security case, the New York Times reported.

Sources involved in the investigation, speaking on condition of anonymity because of the sensitivity of the case, confirmed to the newspaper that Trump’s campaign team was notified of the hacking earlier this week.

The breach also appears to have targeted prominent figures in the Democratic Party. Staff members from the vice president Kamala HarrisHis campaign and notable figures on Capitol Hill, including Senate Majority Leader Chuck Schumer of New York, were among the targets. The revelations highlight the scale of the cyber attack, which Western cyber security experts have attributed to a hacking group they call “Salt Typhoon”.

The ongoing investigation aims to determine whether the hackers are still lurking in Verizon’s network, gathering information or preparing for further exploitation, the news release said.

The disclosure came in the final stages of a campaign in which Trump’s team was also targeted by the group of Iranian hackers accused of breaching US Republican candidate Donald Trump’s campaign emails, who were able to release the stolen material, according to the agency by Reuters press. The hackers, believed to be linked to Iran’s Basij paramilitary force, shared the emails with a Democratic political operative who published them on the website of his PAC, American Muckrakers, and distributed them to independent journalists . That material includes internal Trump campaign discussions with advisers on various election topics, the report said.

The hacking group, known as Mint Sandstorm or APT42, allegedly compromised the accounts of several members of the Trump campaign between May and June. The US Department of Justice has charged three Iranian hackers with the breach, warning they still pose a threat to campaign staff. If convicted, the hackers could face prison terms and fines. The leak highlights, the report said, Iran’s continued efforts to interfere in the US election, despite recent accusations and warnings from Homeland Security. It said attempts to reach the accused hackers were unsuccessful.

FBI and CISA investigate cyber activity in China

The FBI and the Cybersecurity and Infrastructure Security Agency (CISA) issued a joint statement on October 25 confirming an ongoing investigation into unauthorized access to US telecommunications infrastructure by actors affiliated with the People’s Republic of China.

His statement read: The US government is investigating unauthorized access to commercial telecommunications infrastructure by actors affiliated with the People’s Republic of China. After the FBI identified specific malicious activity targeting the sector, the FBI and the Cybersecurity and Infrastructure Security Agency (CISA) immediately notified affected companies, provided technical assistance and quickly shared information to help other potential victims. The investigation is ongoing and we encourage any organization that believes they may be a victim to contact their local FBI or CISA office. Agencies across the U.S. government are collaborating to aggressively mitigate this threat and are coordinating with our industry partners to strengthen cyber defenses in the commercial communications sector.