The National Association of Head Teachers (NAHT) and the Association of Chief Police Officers (ACPO) have reached agreement following a case in which heads were left to decide themselves what precautions to take, and whether to inform parents.

Announcing the details of a protocol drawn up by the two organisations, the NAHT's general secretary, David Hart, said the police would take the lead in such situations.

"They must make the decisions (about) whether information about a sex offender should be passed on."

The protection and safety of children was paramount, he said, but no head wanted to spread unnecessary alarm amongst local parents or spark vigilante-style violence.

"If police take a decision that an offender constitutes a risk either to an individual child or to children in general, that information will be passed to local head teachers," Mr Hart said.

David Hart: "Police must have the prime responsibility"

"The police will then tell the head how to deal with that information. For a head then to act otherwise would put them at risk of criticism if they were then to decide to act otherwise.

"But if they act within the guidance, if there were then to be unfortunate consequences, it would be the police who would take responsibility, not the head."

The protocol signed with ACPO would not only help NAHT members, said Mr Hart.

"It will help immeasurably the government's policy on how to deal with sex offenders and reduce public concern."

Mr Hart said he found it inconceivable that a head informed by police about a paedophile posing a danger to children would not pass that information on to parents.

Vigilantism warning

The Association of Chief Police Officers warned of the potential danger of vigilantism if the decision to name released sex-offenders was taken without proper care.

A spokesman for ACPO, Tim Mahoney, speaking on BBC Radio 4's PM programme, said there were several thousand discharged ex-sex offenders in the community at any one time. The police tried, with the probation services, to carry out a risk assessment on each one.

Mr Mahoney said: "There is a danger of a public over-reaction to the numbers of these people in the community.

"We feel that naming them without thinking about it very carefully would raise the dangers of vigilantism, and we've seen many examples of that in recent weeks and months.

"It would tend to drive offenders underground and we have seen examples of that in recent weeks and months.