The UK's intelligence agencies are increasingly obsessed with the use of large-scale data.

The move, which has civilized civil liberty groups, seeks to expand into what is known as the "bulk equipment interference (EI) regime" – the process by which GCHQ can target entire communication networks overseas in a bid to identify individuals who pose a threat to national security.

A letter from the security minister, Ben Wallace, to the head of the intelligence and security committee, Dominic Grieve, quietly filed in the House of Commons library week, states: "Following a review of current operational and technical realities, GCHQ have … EI regime than originally envisaged. "

The 'bulk equipment interference regime' enables GCHQ to hack targets abroad.

The 'bulk equipment interference regime' enables GCHQ to hack targets abroad. Photographer: GCHQ / PA

The expansion of EI is likely to prove highly controversial.

"Scarlet Kim, legal officer at Privacy International, which has taken the government to court over GCHQ's hacking activities abroad. "It therefore gives almost unfettered powers to the intelligence services to who and when to hack."

Potential targets can be extremely large, Kim suggested. "Hacking presents unique and grave threats to privacy and security," she said. Permitting surveillance against whole groups or countries, or across multiple jurisdictions. "

Lord Anderson, the government's independent reviewer of terrorism legislation, stated in his Report of the Bulk Powers Review that "Bulk EI [equipment interference] is likely to be only sparingly used ".

However, the intelligence services that are used in a hacking exercise are no longer effective and so are large-scale hacks are becoming necessary. Anderson's review noted that the top 40 online activities relevant to MI5's intelligence operations are now encrypted.

"This is really alarming to hear because of the time [when the legislation was passing through parliament] There were really robust assurances that would be used sparingly, "said Hannah Couchman, Policy and Campaign Officer at Liberty. "Something that is the exception is moving towards the norm and that's deeply problematic for us."

Wallace's letter concedes that the intelligence agencies do not want to claim some of the consequences of a bulk hacking exercise, claiming: "It is not always possible to adequately foresee the extent of all interferences with privacy at a point of … issue of a warrant. "

Instead, the investigatory powers commissioner wants to make an assessment of the warrant's impact after the hack has taken place. "This is too little, too late," said Couchman, who questioned whether the expansion of bulk equipment interference with other countries, in return for information.

How do you feel about this situation is, "Couchman added. "With bulk powers, the state can hover up and down. Bulk equipment interference powers allow a broad range of hacking activities, including accessing computers and mobile phones. Imagine what the average person has on their devices. "

A government spokesman said: "Equipment interference is subject to the world-leading oversight of the investigatory powers commissioner and any bulk equipment interference warrant must be approved by an independent judicial commissioner before it can be issued."