By Raphael Satter

WASHINGTON, Jan 27 (Reuters) - Meta's WhatsApp messaging service is offering users an advanced security mode, joining a growing number of U.S. tech firms that are letting users opt into stronger protections against hackers in exchange for a more restrictive experience.

The new option, rolling out on Tuesday and called "Strict Account Settings," is a one-click button in WhatsApp's settings that activates a series of defenses.

These include blocking media and attachments from unknown senders, disabling link previews - the thumbnails that appear when a URL is entered into a chat - and silencing calls from unknown contacts. All three have been identified as potential vectors for surveillance and advanced hackers.

In a blog post, WhatsApp said that while all its users' conversations were protected by end-to-end encryption, "we also know that a few of our users – like journalists or public-facing figures – may need extreme safeguards against rare and highly sophisticated cyberattacks."

Meta Platforms META.O is the third major tech firm to offer a security boost for high-risk users.

In 2022, Apple AAPL.O launched "Lockdown Mode," which it describes as "an optional, extreme protection" designed for the "very few individuals" who might be targeted by advanced digital threats. Available on iPhone and macOS, the feature disables most message attachment types and link previews and includes restrictions on FaceTime calls and web browsing.

Last year, Alphabet's GOOGL.O Android began offering "Advanced Protection Mode," for users with "heightened security awareness."

Like "Lockdown Mode", Alphabet's more secure option trades some functionality for enhanced security, including restricting users from downloading potentially risky apps from outside its in-house Play Store.

A researcher who helps defend civil society figures from hacking said WhatsApp's announcement was "a very welcome development."

The feature will help protect dissidents and activists while encouraging other tech firms to up their game, said John Scott-Railton, who works at The Citizen Lab, a research group based out of the University of Toronto.

"My hope is that others follow suit," he said.

(Reporting by Raphael Satter; Editing by Himani Sarkar)

((raphael.satter@tr.com; +1 202 430 9389;))