Companies are using free smartphone apps as ‘fronts’ to allow them to spy on users’ text messages, intercept calls and even track their location, it was claimed yesterday.

By accepting little-read terms and conditions when downloading apps, consumers give developers the right to harvest vast swathes of private information.

Facebook insists that people using its Android smartphone app agree to give them permission to read their text messages, although the internet giant said it had not yet taken advantage of this right.

Privacy campaigners criticised the abuse of personal information. Nick Pickles, director of Big Brother Watch, described the apps market as ‘an unregulated Wild West’.

Emma Draper, of the Privacy International campaign group, said: ‘Your personal information is a precious commodity, and companies will go to great lengths to get their hands on as much of it as possible.’

The Facebook app has been downloaded to Google’s Android smartphones more than 100million times, yet few of its users are thought to know that they have agreed to give Facebook the right ‘to read SMS messages stored on your device or SIM card’. Apps are also used to identify the location of users through global positioning software and access the phone numbers and email addresses of their contacts.

A spokesman for Facebook said the request for permission to read text messages was to allow the app to read and write data between itself and the phone’s SMS feature, rather than for the company to trawl individuals’ messages.

He added: ‘If Facebook ultimately launches any feature that makes use of these permissions, we will ensure that this is accompanied by appropriate guidance.’