Thousands of school children are potentially being fingerprinted, the Liberal Democrats claim.
A survey of Local Education Authorities (LEAs) discovered 285 schools regularly fingerprint pupils and store their biometric details on record, adding the real figure could be higher.
Despite this, the Department for Education and Skills (DfES) has not issued any guidance on when and how biometric data should be collected and stored.
Only a quarter of LEAs have any guidance available and in the vast majority of cases do not know if parental consent was given to collect fingerprints.
Lib Dem education spokeswoman Sarah Teather said: "These figures confirm an extremely worrying situation where schools are fingerprinting pupils without any guidance on whether it is legal to do so.
"Insecure school computers holding precious unique personal information are a gift to identity thieves."
Schools in Alan Johnson's Hull constituency, as well as John Prescott's neighbouring seat and that of former education minister David Miliband, have all confirmed pupil fingerprinting.
"This is happening right under Alan Johnson's nose and he still refuses to act," Ms Teather said.
"An awful lot of people are washing their hands of responsibility while this practice spreads unregulated."
The DfES countered it is for individual schools to decide if they collect biometric data, but confirmed it would shortly be issuing guidance to all schools on best practice when taking and storing such details.
"This is scaremongering. Schools are well used to holding personal data about pupils and they do so working within the Data Protection Act," a spokesman said.
The Liberal Democrats are encouraging parents to write to the government to push for regulation across all LEAs, as well as find out whether their child's school fingerprints its pupils.