Government surveillance of all children, including information on whether they eat five portions of fruit and vegetables a day, will be condemned tomorrow as a Big Brother system.

Experts say it is the biggest state intrusion in history into the role of parents.

Changes being introduced since Victoria Climbié's death from abuse include a £224 million database tracking all 12 million children in England and Wales from birth. The Government expects the programme to be operating within two years.

But critics say the electronic files will undermine family privacy and destroy the confidentiality of medical, social work and legal records.

Doctors, schools and the police will have to alert the database to a wide range of "concerns". Two warning flags on a child's record could start an investigation.

There will also be a system of targets and performance indicators for children's development. Children's services have been told to work together to make sure that targets are met.

Child care academics, practitioners and policy experts attending a conference at the London School of Economics will express concern about how the system will work.

Dr Eileen Munro, of the LSE, said that if a child caused concern by failing to make progress towards state targets, detailed information would be gathered. That would include subjective judgments such as "Is the parent providing a positive role model?", as well as sensitive information such as a parent's mental health.

"They include consuming five portions of fruit and veg a day, which I am baffled how they will measure," she said. "The country is moving from 'parents are free to bring children up as they think best as long as they are not abusive

or neglectful' to a more coercive 'parents must bring children up to conform to the state's views of what is best'."

The Children Act 2004 gave the Government the powers to create the database.

Experts fear that genuine cases of neglect will be missed in the mass of detail.

"When you are looking for a needle in a haystack, is it necessary to keep building bigger haystacks?" said Jonathan Bamford, the assistant commissioner at the Information Commissioner's office, which promotes access to official information and the protection of personal information.

Keeping check on 11 million or 12 million children, when the justification for the database was that three or four million were in some way "at risk", was "not proportionate", he said.

"The cause for concern indicator against a child's record is expressed in very broad language. For example, it could be cause for concern that a child is not progressing well towards his or her French GCSE."

Arch, the children's rights organisation, was also worried. It said: "Government databases have a dreadful record."

It was revealed this year that more than half a million children had been entered on a DNA database created to record known offenders, even though many had never been charged with an offence.

Eight-year-old Victoria Climbié died in 2000 while living with her aunt, Marie-Therese Kouao, and her aunt's boyfriend, Carl Manning, despite having been seen by dozens of social workers, nurses, doctors and police officers.

The Department for Education and Skills said: "We need to ensure that professionals work across service boundaries for the benefit of children.

"Our proposals balance the need to do everything we can to improve children's life chances whilst ensuring strong safeguards to make sure that information stored is minimal, secure and used appropriately.