Computers in thousands of locations have been locked by a programme that demands $300 (£230) in Bitcoin.
Countries including Britain, America, China, Russia, Spain, Italy, Taiwan and 74 other countries have reported infections due to this cyber-attack.
According to expert opinion these incidents around the world are interconnected.
According to cyber security expert Jakub Kroustek at Avast, it is a grave situation.
Another expert noted that the number of organisations that came under the ransomware cyber-attack could increase.
The UK's National Health Service (NHS) computers have been infected by this cyber-attack and certain networks have crashed, according to health officials.
Hence patients seeking emergency treatment have been transferred to other hospitals.
It is also reported that several institutions in Spain too had come under this cyber-attack.
Spanish telecoms giant Telefonica, power firm Iberdrola and utility provider Gas Natural - suffered from the outbreak. There were reports that staff at the firms were told to turn off their computers.
Turn off computers:
Some firms had asked their employees to immediately shut down their computers, while an Italian university student had posted screen shots of his affected computers.
A computer expert warned that this cyber-attack was fast spreading throughout European organisations.