Japan and China have fallen victim of a global "ransomware" cyberattack that has created chaos in 150 countries as Microsoft pinned blame on the US government for not disclosing more software vulnerabilities.

The initial attack, known as "WannaCry," paralyzed more than 200,000 computers, including those which that run Britain's hospital network, Germany's national railway and other companies and government agencies worldwide, in what's believed to be the biggest online extortion scheme ever.

Nissan Motor confirmed on Monday some units had been targeted, but there was no major impact on its business.

Hitachi spokeswoman Yuko Tainiuchi said emails were slow or not getting delivered, and files could not be opened. The company believes the problems are related to the ransomware attack, although no ransom is being demanded. They were installing software to fix the problems.

The Japan Computer Emergency Response Team Coordination Center, a non-profit providing support for computer attacks, said 2,000 computers at 600 locations in Japan were reported affected so far.

A few individuals also reportedly were affected.