Deloitte LLP has revealed that it has been targeted by a cyberattack that let hackers access data from an internal email platform.

The auditing and consulting firm said in a statement Monday that it's currently informing the clients affected and has notified governmental authorities after it became aware of the incident.

Deloitte said "very few" clients were impacted, and has drafted outside help to review its security.

The email platform was reportedly stored on Microsoft's Azure cloud platform.