Nick Pickles, director of Big Brother Watch, which campaigns on privacy, civil liberties and levels of surveillance, said GCHQ "has serious questions to answer" after reports claimed that British spies could snoop on hundreds of millions of text messages.
If an interception warrant for an individual is not in place, it is illegal to look at the content of a message.
Descriptions of content derived metadata suggest the content of texts is being collected and inspected in bulk and if this is the case GCHQ has serious questions to answer about whether it is operating under a perverse interpretation of the law cooked up in secret.
The telecoms companies providing our mobile phone services need to urgently reassure their customers that they are not handing over our data in bulk to the UK or US governments.
More top news
At least 17 people trapped inside an ammunition depot in India when a fire broke out are feared to have died.
Strong winds and rain, heavy at times in the south-east, are forecast for the UK on Tuesday.
The plan to scrap the VAT could save taxpayers £2 billion if Britain left the EU, lead Leave campaigners claim.