WhatsApp, one of the most popular apps in the world, contravenes international privacy laws because it forces users to provide access to their entire address book according to Canadian and Dutch data center.
WhatsApp, ranking as one of the world's top five best-selling apps, is an instant-messaging application for smartphones including android,Apple and many others.
Based at California it provides a free internet alternative to SMS, or text messaging, sending more than a million messages a day.
The Office of the Privacy Commissioner of Canada (OPC) and the Dutch Data Protection Authority, in a joint report released on Monday, said that it had violated privacy laws as users have to provide access to all phone numbers in their address book, including both registered users and non-registered users of the app.
WhatsApp was not immediately available to comment.
The investigators found that WhatsApp retained the mobile numbers of non-registered users and was against the laws of privacy.
In September 2012, whatsapp updated its app with encryption for its service, partly in response to concerns raised by the investigation.
The Dutch agency made sure it continued to follow the app's foot steps and would penalize if the privacy issues were continued.