This week hundreds of London Underground cleaners are beginning a protest against the introduction of fingerprint recognition machines. Their employers, Danish firm ISS UK, want to introduce a new biometric clocking-in system for their staff. But the RMT Union, which represents the cleaners, says they will refuse to cooperate.

"This is a gross violation of people's individual space," John Leach of the RMT Union told DW. "We're totally unconvinced, we're totally disgusted and we're not going to do it. We've had a secret ballot of our members, conducted completely in order with legislation, and they have voted nearly 100 percent to do this."

Ninety-eight percent of cleaning staff voted against fingerprinting

So for now, the cleaners will continue to use their old clocking-in system. ISS UK has defended the measure, telling local media, "it's about making sure we have the right people - verified and trained - in the right place at the right time."

Biometrics go mainstream

The row about the use of biometrics - which includes fingerprinting, facial recognition and iris recognition - has come to the forefront again with the announcement of Apple's latest iPhone, which incorporates a fingerprint recognition button.

It's not the first device in the industry to do so - some mobile hard drives from the French firm LaCie come with a fingerprint lock - but it's a sign that the technology is entering the mainstream.

"If you were to take back fingerprint technology ten years ago, it was very much associated with policing," says John Tonkiss of Human Recognition Systems, a company that provides biometric identification solutions to commercial organisations. "But in the last three to four years in particular, the use of biometrics, a whole variety of biometrics and fingerprints in particular, have become much more commercial."

There are concerns about the reliability of the technology, and in particular the storage of data.

A fingerprint is not like a password that you can simply change if someone hacks into a database and gains access to it. Our fingerprints are totally unique - they belong only to us. Even identical twins, who may share DNA patterns, will have different fingerprints.

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"There are still residual scientific doubts about how secure the systems are," says Nick Pickles of Big Brother Watch, a campaign group which aims to protect privacy and defend civil liberties.

"How secure is the data?" he asks. "If someone were to gain access, can they regenerate a fingerprint from the data that is stored?"

But the technology is becoming increasingly common.

A number of schools have even tried using biometrics to identify pupils in canteens and libraries.

"One of the ridiculous things that happened is that some primary schools started using [the technology] - so with very young children - and they quickly realised that it wasn't very good when it was covered in play dough and sand and paint and small children's dirty hands were using it," says Pickles.

"Cost effective"

Similar systems are also in use to identify workers accessing construction sites. Those in the industry defend its safety and reliability.

"We store the data on local applications, we don't take that data away. It's the record of the events that are stored, rather than the biometric data itself," says John Tonkiss of Human Recognition Systems.

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"Biometrics give us an absolute assurance that the person is who they say they are... It just makes identity vetting and identity verification far more cost effective," he explains.

And Tonkiss says it's something we will likely be seeing much more of in years to come.

"More and more mobile devices will have fingerprint-ready readers fairly shortly," says Tonkiss. "So that's now the notion that one can bring one's own biometric device, which means we can get increased confidence of personal identity in a very cost-effective, quick and ready manner."

He cites Internet shopping, online banking and airports as potential uses for mobile devices in fingerprint recognition.

But Nick Pickles of Big Brother Watch says people need a choice: "Forcing people to only use a system which involves their fingerprints…we think that should never be the case, and there should always be an alternative."