A notorious strain of ransomware known as WannaCry, which caused global computer chaos last month after spreading to hundreds of thousands of machines in 150 countries, has now infected dozens of speed and red light cameras in Victoria, Australia.

A total of 55 cameras were impacted by the malware, which is able to lock down vital files and demand a ransom for their return, however officials stressed it was a targeted cyberattack. Instead, the incident has been blamed on 'human error', likely on the part of a camera technician.

According to the 3AW morning radio show, which spoke directly to investigators, all of the cameras remain online but a number reportedly had to be re-booted, which caused intermittent outages.

The central network the cameras are connected to is not Windows based and therefore is immune.

"A system patch has been applied, which prevents the spread of the virus," a Justice and Regulation spokesperson told the programme.

"The Department is in the process of removing the virus from the affected cameras. The remaining sites will be rectified in the next couple of days.

"The software virus has not impacted the accuracy of the camera system. All infringements during this period have been captured correctly, and no infringements have been affected by the virus."

Victoria Sheriff Brendan Facey confirmed the police had been aware of the infection for a number of days and was working with the camera vendor – called Redflex Traffic Systems – to resolve the issue.

"Because the camera's processes had detected the virus [they have] been rebooting," he said. "That's how we were able to detect it and get in there and start patching them and reinstalling software." He said the majority had been fixed, with "dozen or so" still infected.

A full investigation has been launched, Facey said.

WannaCry is a form of ransomware super-powered by exploit code once used by the US National Security Agency (NSA). In April 2017, a group known as The Shadow Brokers leaked a slew of so-called cyberweapons, but some experts suspected involvement of North Korean hackers.

This week, Japanese car manufacturer Honda revealed one of its Tokyo-based facilities had to be shut down for 24 hours after being infected with the WannaCry ransomware.