The heads of MI5 and FBI warned of the growing long-term threat posed by China to UK and U.S. interests, in their first joint appearance on Wednesday.

MI5 Director General Ken McCallum said the service has already "more than doubled our previously-constrained effort against Chinese activity of concern," adding it was running seven times as many investigations as in 2018.

FBI Director Christopher Wray said that the Chinese government "poses the biggest long-term threat" to economic and national security, for the UK, the U.S. and allies in Europe and elsewhere.

"The Chinese government is trying to shape the world by interfering in our politics (and those of our allies, I should add)," Wray said, saying Beijing had directly interfered in a Congressional election in New York this year, as it did not want a candidate who was a critic and former protester at Tiananmen Square to be elected.

Wray warned that the Chinese government "poses an even more serious threat to Western businesses than even many sophisticated businesspeople realize," and is "set on stealing your technology."

The Chinese governement's hacking program is "bigger than that of every other major country combined," according to Wray.