US blames North Korea for May cyber-attack

The White House claimed that North Korea was "directly responsible" for the WannaCry malware attack that hit more than 30,000 computers in hospitals, businesses and banks across 150 nations in May and caused billions of pounds in damage.

Thomas Bossert, an aide to the US president, made the accusation in Monday's edition of the Journal, officially blaming Pyongyang "based on evidence".

Number 10 said in November that it was "all but certain" that the rogue nation was responsible for the attack that left Windows users locked out of their devices and their contents unless they paid a ransom.

"North Korea has acted especially badly, largely unchecked, for more than a decade, and its malicious behaviour is growing more egregious. WannaCry was indiscriminately reckless," Bossert said.

"As we make the internet safer, we will continue to hold accountable those who harm or threaten us, whether they act alone or on behalf of criminal organizations or hostile nations," he added. "The tool kits of totalitarian regimes are too threatening to ignore."

The White House was expected to make an official statement on Tuesday.