Supermarket chain Coop had to temporarily close almost all of its 800 stores in Sweden on Saturday.

This is due to a cyber attack that paralyzed the cash registers.

According to a Swedish subsidiary of the IT group Visma, there is a connection with the major cyber attack that was carried out on Friday on the American company Kaseya, which manages IT systems for many companies.

The group behind the hack is known as REvil, according to cybersecurity firm Recorded Future.

The Russian hacking group was also behind the hack at meat-processing company JBS, which shut down a significant portion of the U.S. meat-processing industry last month.

The company paid a ransom of $11 million after the cyber attack.

That attack came not long after a major cyber attack against the American Colonial Pipeline.

The attack caused a major oil pipeline to be temporarily shut down in April, causing shortages of petrol at filling stations and soaring fuel prices.

DarkSide, also a Russian hacker collective, was behind the hostage taking of the system.

Ransomeware is an increasing problem worldwide.

According to security firm Emsisoft, at least $18 billion was paid in 2020 to cybercriminals who deploy ransomware.

Coop has a market share of 20 percent in the Swedish supermarket sector and an annual turnover of approximately 1.5 billion euros.