WhatsApp on Friday postponed a data-sharing change as users concerned about privacy fled the Facebook-owned messaging service and flocked to rivals Telegram and Signal.

The smartphone app, a huge hit across the world, canceled its February 8 deadline for accepting an update to its terms concerning sharing data with Facebook, saying it would use the pause to clear up misinformation around privacy and security.

"We've heard from so many people how much confusion there is around our recent update," WhatsApp said in a blog post.

"This update does not expand our ability to share data with Facebook."

It said it would instead "go to people gradually to review the policy at their own pace before new business options are available on May 15."

WhatsApp's new terms were unpopular among users outside Europe who do not accept that they were given a deadline to be cut off from the service.

The update concerns how merchants using WhatsApp to chat with customers can share data with Facebook, which could use the information for targeted ads, according to the social network.

"We can't see your private messages or hear your calls, and neither can Facebook," WhatsApp said in an earlier blog post.

"We don't keep logs of who everyone is messaging or calling. We can't see your shared location and neither can Facebook."

Location data along with message contents is encrypted end-to-end, according to WhatsApp.

"We're giving businesses the option to use secure hosting services from Facebook to manage WhatsApp chats with their customers, answer questions, and send helpful information like purchase receipts," WhatsApp said in a post.

"Whether you communicate with a business by phone, email, or WhatsApp, it can see what you're saying and may use that information for its own marketing purposes, which may include advertising on Facebook."

- Tapping Telegram -
Encrypted messaging app Telegram has seen user ranks surge on the heels of the WhatsApp service terms announcement, said its Russia-born founder Pavel Durov.

Durov, 36, said on his Telegram channel this week that the app had over 500 million monthly active users in the first weeks of January and "25 million new users joined Telegram in the last 72 hours alone."

WhatsApp boasts more than two billion users.

"People no longer want to exchange their privacy for free services," Durov said without directly referring to the rival app.

Encrypted messaging app Signal has also seen a huge surge in demand, helped by a tweeted recommendation by billionaire tech entrepreneur Elon Musk.

In India, WhatsApp's biggest market with some 400 million users, the two apps gained around four million subscribers last week, financial daily Mint reported, citing data from research firm Sensor Tower.

WhatsApp has sought to reassure worried users in the South Asian country, running full-page adverts in Wednesday's newspapers, proclaiming that "respect for your privacy is coded into our DNA".

Telegram is a popular social media platform in a number of countries, particularly in the former Soviet Union and Iran, and is used both for private communications and sharing information and news.

Durov said Telegram has become a "refuge" for those seeking a private and secure communications platform and assured new users that his team "takes this responsibility very seriously."

Telegram was founded in 2013 by brothers Pavel and Nikolai Durov, who also founded Russia's social media network VKontakte.

Telegram refuses to cooperate with requests from authorities to hand over encryption keys, which resulted in its ban in several countries, including Russia. 

Last year, Russia announced that it will lift its ban on the app after more than two years of unsuccessful attempts to block it.