Japanese online retailer Askul Corp said Thursday that it will fully resume services for corporate customers in early December after a cyberattack last month severely disrupted its operations.

The Tokyo-based company has been taking orders by fax from some corporate customers, including healthcare facilities. It plans to expand its logistics bases later this month, expecting its shipping capacity to recover to around 20 percent of normal levels.

Askul has suspended online order and shipping operations since Oct 19 after a cyberattack led to the leakage of private information. A hacker group believed to be Russian has since claimed responsibility for the attack.

Concern has been growing that the supply of medical equipment across Japan could become severely strained if Askul's services remain suspended for a month, as temperatures drop and illnesses such as colds and other infectious diseases are likely to spread.

Ryohin Keikaku Co, operator of the Muji retail brand, was also affected by the incident and forced to suspend online sales, as it had outsourced shipments from its internet stores to a logistics firm under Askul.

The timeline for restoring operations at its logistics company differs from that of Askul, the retailer said.