The latest contender in the range of such mobile phones is Blackphone, which runs on a customized version of Google's (GOOG.O) Android software and encrypts texts, voice calls and video chats was launched in Spanish Pavilion at the annual Mobile World Congress industry fair in Barcelona on Monday.

It aims to tap into the market for so-called mobile security management (MSM) products, which was estimated to be worth USD 560 million in 2013 and is expected to nearly double in size to USD one billion a year by 2015, according to ABI Research.

Separately, Deutsche Telekom (DTEGn.DE) said it is also preparing to launch a smartphone app that encrypts voice and text messages, making it the first major network operator with a mass market-compatible product that will be rolled out to all its users.

Edward Snowden set off a global furore when he told newspapers last year that US National Security Agency (NSA) was mining the personal data of users of firms such as Google (GOOG.O), Facebook (FB.O) and Skype under its Prism programme.

Swisscom (SCMN.VX) said last week that it saw a tripling of downloads for its secure messaging service iO, which encrypts chats and calls and stores all its data in Switzerland. Swiss mobile messaging services myENIGMA and Threema also encrypt users' exchanges.

The Blackphone, which chose Switzerland as its home base because privacy there is a constitutional right, is the result of cooperation between US security software company Silent Circle and Spanish handset maker GeeksPhone.

The device will retail for USD 629 including a two-year subscription to the Silent Circle encryption service, which normally costs USD 120 a year, as well as a one-year subscription for three other parties.

"We are aiming to sell hundreds of thousands devices," Blackphone's managing director Toby Weir-Jones told reporters.

"This is a phone for everyone - whether you are an executive who likes to bring his device to work or you are a privacy-minded citizen who just wants to make sure that the internet is not looking over your shoulder,” Toby Weir-Jones said.