Toshiba TFIS, which specialises in printers, was "hacked on May 4 by DarkSide ransomware which had already attacked numerous companies of all sizes", the company said in a statement.

The Japanese conglomerate said in a separate statement that the attack was limited to part of Europe and the hackers did not get access to client data.

A Toshiba spokesman told AFP that the attack did not hit other parts of the group.

"The amount of work lost was minimal," Toshiba TFIS said.

The company said it did not detect any data leak, though social media images of a DarkSide statement show the group claimed to have made a trove of information public.

The United States says DarkSide was behind the ransomware attack that forced the shutdown of the largest oil pipeline in the country.

Ransomware attacks use a type of malware that encrypts files on an infected computer, normally via an email attachment or download, and demands money to unlock them.

Colonial Pipeline announced Thursday the restart of its entire network and resumption of fuel deliveries, days after the attack.

On Friday, Ireland's health authority said it had shut down its computer systems after a "significant" ransomware attack by "an internationally operated criminal operation".

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TOSHIBA