Google said Thursday its popular Gmail service would use encryption to thwart snooping, in the latest move by the tech sector reassuring customers following revelations about US surveillance programs.

"Your email is important to you, and making sure it stays safe and always available is important to us," said Gmail engineering security chief Nicolas Lidzborski in a blog post.

"Starting today, Gmail will always use an encrypted HTTPS connection when you check or send email.. Today's change means that no one can listen in on your messages as they go back and forth between you and Gmail's servers -- no matter if you're using public WiFi or logging in from your computer, phone or tablet."

Google has already begun scrambling most of the traffic at its websites as technology firms grapple with moves by US intelligence agencies to spy on what people are doing and sharing online.

And similar moves have been announced by Yahoo, Microsoft and Facebook to use encryption that limits the ability of a third party to read messages or emails.

US tech firms have been ramping up encryption since last year's explosive revelations about the vast surveillance capabilities of the National Security Agency and other intelligence services, based on leaked documents.

Lidzborski said Google's latest move "ensures that your messages are safe not only when they move between you and Gmail's servers, but also as they move between Google's data centers -- something we made a top priority after last summer's revelations."

Some reports say the NSA had been able to access data centers of Google and other Web firms.

Experts say encryption generally prevents outsiders from intercepting a person's messages or documents but that a persistent effort can gain access through malware or other methods which trick a person into revealing passwords.

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