Parents of children at Hertfordshire Jewish nurseries may be asked for a voluntary contribution towards the cost of services such as kosher meals and security.

Hertfordshire County Council is among local authorities applying a rigid interpretation of a government code of practice requiring three- and four-year-olds to receive 15 hours' free nursery education for 38 weeks a year. The code prohibits the charging of additional fees in connection with the provision. The policy is scheduled to be implemented in Herts next month.

The government announced last week that it would be reviewing the code after nationwide protests.

Susan Gray, head of Gilah nursery at Borehamwood Synagogue, said an email from the county council suggested that although the code is "very clear that parents are entitled to receive 15 hours of early years provision which is free at the point of delivery and is not dependent on paying for additional services, parents may be asked [not required] to pay a voluntary contribution."

Mrs Gray said it could mean that "we may make the payment of a contribution towards security fees a condition of offering a child a place at Gilah - and parents will have to sign a contract accepting this. But once a child is in the school, we will have to provide the 15 hours of free education with no strings attached. We would then hope that the parents would continue to pay the contribution voluntarily. We must charge these extra fees in order to keep their children safe."

Rivka Bicks, who runs the Little Bicks nursery on the premises of the Ohr Yisrael (Federation) Synagogue in Borehamwood, has also asked parents for a voluntary contribution towards the cost of security and kosher food. "Reaction so far has been positive, but this is not really a long-term solution," she said.

"We are hoping that the government will have a rethink on the 'top-up' charges."