Hundreds of school children fingerprinted for their lunch

The statistics show 68 schools have introduced the systems, which often use fingerprint technology.

The figures, obtained by the Scottish Liberal Democrats through a freedom of information request, show there are another ten schools which have the technology but do not yet use it.

Robert Brown, Liberal Democrat spokesman on justice, described the extent of the use of ID systems in schools as "rather worrying".

Civil rights campaigners warned such measures were a step closer to a "Big Brother" society and treated children with suspicion and contempt.

In one secondary school in West Lothian there is a hand pad system in place for primary school pupils housed there temporarily to gain access to toilets.

If fingerprint technology is used, an image of the child's fingerprint is not kept, but if palm recognition is used, an image of the palm is encrypted and stored, claim the Lib Dems. "If the vast majority of Scotland's schools can let children move round the premises and pay for their lunch without biometric identification, it is difficult to see how it is necessary for these 68 schools," said Mr Brown. "Public bodies have shown in the past that they are not always to be trusted with sensitive personal data.

"If the finger or palm prints of children as young as four years old got into the wrong hands, it could have significant consequences. We need to be sure that the biometric data is kept secure and destroyed as soon as possible - and certainly after pupils leave school.

"Liberal Democrats in government have scrapped the invidious plans for ID cards. We really don't want to see this coming in through the backdoor through Scottish classrooms."

Human rights lawyer Aamer Anwar, said: "This is the introduction of Big Brother by the back door as potentially it could allow the state to justify widespread use. It almost normalises it and allowing its use in schools, where it doesn't really harm anyone, allows them to say it's in schools already and widen its introduction."

He pointed to several occasions in the past where government ministers had lost data.

He added: "Who is responsible for this data and its storage? We are talking about children."

Ann Ballinger, general secretary of the Scottish Secondary Teachers' Association (SSTA), said: "There is an argument for it, for example in preventing easy identification and potential bullying of children receiving free school meals.

"However, there are other ways of tackling that, such as having all children using cards with cash pre-loaded. Then no-one can tell who put the money on to it.But we would need to be reassured that the data is secure before we would support this."

A Scottish Government spokesman said the figures showed just 3 per cent of Scotland's schools used the technology. He added: "The decision on whether or not to use biometric identification in schools is ultimately one for education authorities but decisions must reflect Scottish Government guidance, which is clear that schools should be very cautious about such an approach."