Anybody who objects to their personal details going on the new “Big Brother” ID cards database will be banned from having a passport.
James Hall, the official in charge of the supposedly-voluntary scheme, said the Government would allow people to opt out – but in return they must “forgo the ability” to have a travel document.
With one in every eight people saying they will refuse to sign-up, up to five million adults could effectively be refused permission to leave the country.
Campaigners reacted to Mr Hall’s remarks with fury, saying they were yet more evidence of the lurch towards “Big Brother” Britain.
Phil Booth, of the NO2ID group, said: “The idea that ID cards scheme is voluntary, and people can opt-out, is a joke.
“There are all sorts of reasons why people need to travel, not just for holidays. There is work, visiting relatives.
“What are these people supposed to do? It stretches the definition of voluntary beyond breaking point. They will go to any length to get personal information for this huge database. Who knows what will happen to it then?”
Mr Hall, chief executive of the Identity and Passport Service, delivered his warning during a Downing Street “webchat”.
One concerned member of the public, Andrew Michael Edwards, asked what would happen to people who refuse to join the £5.4 billion scheme.
Mr Hall replied: “There is no need to register and have fingerprints taken – but you will forgo the ability to have a passport”.
Officials later explained the meaning of his remark.
The first ID cards will be issued in 2009, to anybody who applies for a passport.
People will be required to give fingerprints, biometric details such as a facial scan and a wealth of personal details – including second homes, driving licence and insurance numbers.
All will be stored on a giant ID cards Register, which can be accessed by accredited Whitehall departments, banks and businesses.
While The ID Cards Bill was going through Parliament, peers agreed an “opt out” with Ministers for people who needed a passport, but did not want to participate in the ID cards scheme.
It was the only way the Lords would accept the legislation, amid howls of concern that it represents yet another move towards a surveillance society.
But, as Mr Hall’s comments this week make clear, the opt-out only applies to being physically issued with a card.
In order to get a passport, people will still have to hand over all their personal details for storage on the ID cards Register – where they will be treated in the same was as those who agreed to sign-up.
They simply avoid getting the card – even though they will have to pay the full combined price of £93 for an ID card and passport.
It means that, despite the Government repeatedly insisting the scheme is voluntary, the only way to avoid signing-up is to never obtain or renew a passport.
Therefore, anybody who objects to ID cards on principle and wants to keep their personal details private must remain in the UK for the rest of their lives.
Critics said it was clear ID cards were being made compulsory by stealth.
Some 6.6million people apply for travel documents each year.
Mr Booth said legal challenges were inevitable, as restricting the right of free movement is a grave breach of human rights law.
A YouGov survey, published three months ago, found 12 per cent of Britons would refuse to take part in the scheme, even if it meant paying a fine or serving a prison sentence.
Mr Booth predicted many of this group would be prepared to bring test cases to challenge the Government’s position in court.
Liberal Democrat home affairs spokesman Nick Clegg said: “This comment confirms long standing suspicions that the government’s claim that the ID database will be voluntary is simply not true. The voluntary claim is serving as a fig leaf for a universal compulsory system.
“Once again the government’s ID card plans are being pursued behind the backs of the British people.”
Labour has become increasingly obsessed with the introduction of ID cards, claiming they will help to beat fraud and illegal immigration.
But both the Conservatives and Liberal Democrats have fiercely opposed the scheme, amid concerns costs could spiral out of control.
Academics have predicted the final bill could reach up to £20 billion.
There are also concerns Ministers could be tempted to strike financial deals to pass on personal details, in a bid to recoup some of the enormous costs.
If the Tories win power, it will be scrapped immediately.
Mr Hall’s comments will fuel the suspicion that Ministers are involved in a desperate race against time to get the project off the ground, and get as many people’s details as possible before the next General Election.
The Home Office said it had never hidden the fact anybody refusing to give their biometric and other personal details to the ID cards database would not be eligible for a passport.
A spokesman said it was more cost effective to link the issuing of passports and ID cards, rather than allow people to register their details for one but not the other.