Dentsu reported early Tuesday a cyber security incident affecting part of data unit Merkle’s network, that effected some client, supplier and employee data. 

The firm said that law enforcement authorities have been notified, and cyber security experts have been brought in as part of the investigation, which is still ongoing. Merkle’s UK operations were impacted, but it is not clear which other regions (if any) were impacted by the attack. 

It was not immediately clear how extensive the incident was, but the company stated: “The investigation identified that certain files were taken from Merkle’s network. “   

“A review of those files determined that they contained information relating to some clients, suppliers, and current and former employees. Although our investigation remains ongoing, we have begun the notification process in accordance with applicable law.” 

There were reports that some of the files taken included bank and payroll details, salary information, and personal contact details. 

Dentsu said that when it discovered what it termed “the unusual activity,” it initiated response protocols, including taking certain systems offline and “implementing measures to contain the issue.” Those systems are now back online, the firm stated. 

Many details remain unclear. Dentsu said the “financial impact to the business is not known” at this time.