Chinese hackers are actively listening in on calls and intercepting communications in real time, says a US senator.

Top executives from the U.S. telecom industry and national security officials gathered at the White House to address concerns over a Chinese cyber-espionage campaign targeting high-ranking U.S. political figures.

The Chinese government espionage campaign that has deeply penetrated more than a dozen U.S. telecommunications companies is the “worst telecom hack in our nation’s history — by far,” a senior U.S. senator told The Washington Post in an interview this week.

A breach of telecoms companies that the United States said was linked to China was the "worst telecom hack in our nation's history - by far", the chairman of the Senate Intelligence Committee told the Washington Post on Thursday.

Telecoms hack on US government officials is 'worst in nations history' and 'the barn door is still wide open' says senator