Those who do not agree to the new arrangements will be blocked from using basic features, effectively barring them from the app.

The new policy has prompted some users to contemplate switching to other encrypted messaging apps, such as Signal and Telegram. Telegram reported on Tuesday that it had added 25 million users in the previous 72 hours, while Signal, created by WhatsApp co-founder of Brian Arton, became the most popular social media offering on Apple app store in the past week.

Signal sees meteoric rise as people look for WhatsApp alternatives

Chung said Facebook had to clarify to users the new arrangements for sharing personal data – for instance, what data was subject to the change and how it would be used.

She also questioned Facebook’s explanation that the new privacy policy was only related to business communications.

If that were the case, Chung asked, “Why does the change apply to all users?”

She raised questions as to the purpose of sharing user data with other Facebook-owned companies, claiming the new policy could reverse the app’s previous practice of not sharing users’ contact lists with Facebook.

“But the new terms of the privacy policy cover a substantial amount of personal data including the contact lists,” she said.

Chung added that the WhatsApp policy change was a commercial decision rather than a legal issue, and did not infringe any existing privacy data protection rules in Hong Kong.

Hong Kong privacy watchdog urges WhatsApp to pump brakes on policy changes

WhatsApp in a tweet on Tuesday said it wanted to “address some rumours” about the privacy changes, and included a list of things that would not be collected under the new arrangements.

In addition to not being able to read the content of messages or hear audio calls due to its end-to-end encryption, WhatsApp said it did not compile logs of messages or calls. It also said it could not see or share users’ locations, and that it would not share users’ contacts with Facebook.

In a FAQ on the new privacy changes, WhatsApp said they would enable corporate users to access Facebook services, such as in-app shopping and secure hosting. But communicating with such a business, it noted, meant that a third party could then “use that information for its own marketing purposes, which may include advertising on Facebook”.

“To make sure you’re informed, we clearly label conversations with businesses that are choosing to use hosting services from Facebook,” the FAQ said.

US sues to break up Facebook, seeking divestment of Instagram and WhatsApp

A WhatsApp spokeswoman told the Post on Monday that if users refused to agree to the privacy updates by the deadline, they could still see message notifications and receive calls, but would not be able to use basic functions such as sending messages or making calls of their own.

She added that there had been “inaccurate information going around” about the changes, and stressed that the encryption protection provided by WhatsApp would remain.

Responding to the privacy commissioner’s comments on Wednesday, the spokeswoman said the company had explained the policy update to hundreds of stakeholders around the world, including ones in Hong Kong.

“We have been in contact with the Office of the Privacy Commissioner for Personal Data throughout this week in regards to their inquiries about the recent WhatsApp policy update, and have provided more information including our most recent public FAQs,” she said.

Only users in the European Union and Britain are exempted from the new data collection policy. The EU’s General Data Protection Regulation has been regarded as the gold standard for strict personal data protection, and has been copied by numerous countries outside of the bloc.

Turkey’s antitrust board, meanwhile, is looking into the WhatsApp update, and will halt the implementation of the new terms in the country.

Keith Li King-wah, vice-chairman at Hong Kong Wireless Technology Industry Association, said although people could choose to talk to businesses through channels other than WhatsApp, few might wish to do so due to the inconvenience.

“The problem now is everyone doesn’t have the right to choose. They can only agree with the policy, otherwise they can’t use WhatsApp – that’s why people have doubts,” he said.

Li said the public’s concerns were reasonable because Hong Kong did not have enough privacy protection under the law.

He said the Office of the Privacy Commissioner for Personal Data did not have many channels by which to screen whether big overseas corporations were strictly following standards in handling personal data.

“So most of the time, we are just putting our trust in the companies,” he said. “It’s relatively hard to follow up the abuse of personal data through legal proceedings.”

Michael Gazeley, co-founder and managing director of the cybersecurity firm Network Box, said that in terms of data protection, Signal was the best app, followed by Telegram.

“There are 2.8 billion people using WhatsApp around the world, if you don’t use WhatsApp, you may not be able to communicate with people using only that app,” he said. “There is nothing that stops you from having Signal, Telegram and WhatsApp, which are free of charge.”