West Midlands Police tight-lipped on controversial fake phone mast spy technology

International Mobile Subscriber Identity (IMSI) catchers, also known as Stingrays, mimic mobile phone masts and trick phones into connecting with them.

The controversial surveillance technology is used by police agencies worldwide to target the communications of criminals.

However, Stingrays also collect the data of all other phones in the area, meaning innocent people's communications are spied on.

Twenty instances that showed tell-tale signs of Stingray activity were discovered during an investigation in London. It comes as the government's use of spy powers have been criticised by a top lawyer carrying out a review into the data grabbing by the intelligence services and police forces.

West Midlands Police spokeswoman Keiley Gartland said the force would not confirm or deny use of the technology in the region.

Keith Bristow, the Wolverhampton-born director-general of the National Crime Agency, said: "Some of what we would like to talk about to get the debate informed and logical, we can't, because it would defeat the purpose of having the tactics in the first place.

"Frankly, some of what we need to do is intrusive, it is uncomfortable, and the important thing is we set that out openly and recognise there are difficult choices to be made."

And Britain's highest-ranking police officer, the Metropolitan Police Commissioner Sir Bernard Hogan-Howe said: "We're not going to talk about it, because the only people who benefit are the other side, and I see no reason in giving away that sort of thing.

"If people imagine that we've got the resources to do as much intrusion as they worry about, I would reassure them that it's impossible."

The police's refusal to comment on IMSI catchers means, if they are used, it is unclear how they are regulated.

IMSI catchers are available to buy on the internet for around £1,000, raising the possibility that they might be being used by foreign governments, businesses, or criminals to steal citizens' personal data.

The government's data grabbing legislation was branded 'undemocratic, unnecessary, and intolerable' by David Anderson QC who called for a 'clean slate' to overhaul intrusive powers used by authorities to combat terrorism and serious crime, saying the current framework is 'fragmented' and 'obscure'.

The Home Secretary Theresa May said a draft Bill to reform security services' powers to monitor online and other communications will be introduced following Mr Anderson's review.

West Bromwich East MP Tom Watson has been a leading campaigner to limit the levels of government snooping on ordinary residents.

He previously warned that the intelligence and police services are in danger of losing 'public legitimacy' if it is not explained to citizens how and why their data is intercepted and why.

The Express & Star has previously revealed how West Midlands Police has used snooping powers under the Regulation of Investigatory Powers Act (RIPA) nearly 100,000 times in three years, and councils in the Black Country have used them 500 times in the past five years, including on cases of dog fouling and noisy neighbours.