Federal authorities say an investigation into Chinese government hacking efforts has revealed a “broad and significant” cyberespionage campaign mounted by Beijing.

The FBI has been notified of evidence of hacking on the iPhones of two senior officials at one of the presidential campaigns. Sources say the agency is pursuing a lead related to a Chinese hacking group.

A federal investigation into Chinese government efforts to hack into US telecommunications networks has revealed a “broad and significant” cyberespionage campaign aimed at stealing information from Americans who work in government and politics, the FBI said.

The U.S. government’s ongoing probe into China-backed actors’ attempts to hack into U.S. telecommunications infrastructure revealed a “broad and significant” espionage campaign targeted at those in government or political work,