Hackers linked to foreign governments are now behind the majority of "nationally significant¡± cyberattacks targeting the U.K., the country¡¯s top cybersecurity official is set to warn.

Richard Horne, chief executive officer of the National Cyber Security Centre, or NCSC, is scheduled to say in a speech on Wednesday that the country is facing four consequential cyberattacks every week and living through the "most seismic geopolitical shift in modern history,¡± according to a preview of his remarks.

Horne named China, Iran and Russia as key adversaries posing a threat to U.K. cybersecurity.