The popular messaging app WhatsApp asked its some two billion users on Thursday to accept new terms that will allow it to share more information with its parent company Facebook and roll out advertising and e-commerce.

The update sparked criticism among users as they must accept the changes or see their access to the service - which also allows encrypted voice and video calls - cut off from Feb 8.

Facebook aims to monetise WhatsApp by allowing businesses to contact their clients via the platform, even sell them products directly using the service as they already do in India.

"Privacy policy and terms updates are common in the industry and we're providing users with ample notice to review the changes, which go into effect on February 8th," a Facebook spokesperson said.

"All users need to accept the new terms of service if they want to continue using WhatsApp," added the spokesperson.

Instagram and Messenger

The firm said the updated terms will allow additional sharing of information between WhatsApp with Facebook and its other applications such as Instagram and Messenger, such as contacts and profile data, but not the content of messages which remain encrypted.

In the European Union (EU) and Britain, the new terms only allow for the development of functionalities for professional users of WhatsApp Business, a company spokesperson told AFP.

User advocates warned the update was not legal.

"If the only way to refuse (the modification) is to stop using WhatsApp, the consent is forced as the use of personal data is illegal," said Arthur Messaud, a lawyer for La Quadrature du net, an association that defends internet users.

Facebook has come under increasing pressure from regulators as it tries to integrate its services.

The EU fined the US social media giant 110 million euros (S$178.8 million) for providing incorrect and misleading information about its 2014 takeover of WhatsApp concerning the ability to link accounts between the services.

Federal and state regulators in US have accused Facebook of using its acquisitions of WhatsApp and Instagram to squelch competition and filed antitrust lawsuits last month that aim to force the company to divest them.