It was a rare act of continuity at a time of rapidly changing policies at the Department for Education. While Michael Gove was busy carving out his own vision for education, the schools secretary also implemented laws drawn up by the outgoing Labour administration to guarantee full-time teaching to children unable to attend mainstream school.

But the legislation, which only took effect last month, is already in danger of failing because of severe budget and staffing cuts at councils, a report by the Local Government Ombudsman (LGO) has warned.

The move was supposed to guarantee teaching to children unable to go to school because of permanent exclusion or illness. Previously, local authorities only had to provide an amount of teaching that they deemed “suitable”. The new law for the first time defined that as full-time, putting pressure on councils to arrange more teaching in alternative settings, including one-to-one tuition and pupil referral units.

But the LGO is concerned that the reforms could fall at the first hurdle because of the “enormous pressures” faced by local authorities. This “may result in more children missing out on crucial years of education,” its report says.

“The duty to provide full-time education will put an additional burden on local authorities when we are all aware they are facing significant cuts to budgets and staffing levels,” Dr Jane Martin, one of the ombudsmen, told TES.

“This poses the question of how local authorities will meet this requirement. There is a risk that they won’t and will fail in their duties. Both councils and the Department for Education need to have a comprehensive look at this issue.”

There are no reliable figures to show how many children are not in school and not receiving sufficient teaching. Dr Martin said that many local authorities were not aware of their responsibilities, even before the law changed.

The LGO report shows how some councils are failing the most vulnerable children. It features the case of a seven-year-old girl with challenging behaviour who was illegally “unofficially” excluded from school and had to wait seven months to get a place in another primary. It also cites the case of a 14-year-old boy who was refused tuition by his local council when he was suffering from anxiety and could not leave the house, because the authority said “there was no medical evidence to justify it”.

Anne Marie Carrie, chief executive of Barnardo’s, said she shared the LGO’s concerns. “We are particularly concerned about the issue of unofficial exclusions and delays in finding alternative provision for children who have been permanently excluded from school,” she said.

Matt Dunkley, president of the Association of Directors of Children’s Services, said that councils took their responsibilities over children missing education “extremely seriously”.

Mr Dunkley also said that the association was “watching with interest” plans to give more responsibility to schools over pupils that they exclude.

For its part, the DfE has vowed to investigate any cases of non-compliance that are brought to its attention. “We welcome this useful report ... as it will help local authorities deal with a number of commonly occurring situations where a child may not be attending school,” a spokesman said.

Mr Gove has mapped out a number of changes he wants made to alternative education provision, with private sector and voluntary groups to be given a greater role. They will also need sufficient funding if all children are to receive the full-time teaching required by the law.

WHAT LAS MUST DO

The Education Act 1996 says that if a child of compulsory school age cannot attend school for reasons including illness and exclusion, the local authority must make arrangements to provide “suitable education” either at school or elsewhere.

The Children, Schools and Families Act 2010 extends that duty and says local authorities should arrange full-time education for all children in alternative provision.

The teaching must be of a similar quality to that which the child would receive in school, based on a broad and balanced curriculum.