Muji brand store operator Ryohin Keikaku Co said Friday its customer information may have been leaked due to a recent cyberattack on Askul Corp, which provides logistics services to the retailer.

Ryohin Keikaku said names, addresses, phone numbers and order details of customers who shopped via its online shopping site may have been compromised. It has halted service of its internet store since Oct 19, when Japanese online retailer Askul said it suffered a ransomware attack.

Askul also said Friday customer information from companies that use its logistic services may have been leaked due to the cyberattack, warning against fraudulent e-mails that exploit the leaked information.

The internet shopping sites of department store chain operator Sogo & Seibu Co and retailer The Loft Co were also affected by the attack. However, the two companies said that, as of Friday, Askul had reported no confirmed customer information leakage.

Askul has suspended online orders and shipping operations, confirming the leakage of customer information. A hacker group believed to be Russian has claimed responsibility for the attack.