Teachers worried about problems in schools do not know how to raise the alarm because of the expansion of free schools and academies, according to a report published today.

With many schools now outside local authority control, a charity which advises whistleblowers has reported a sharp rise in the number of cases brought to it last year. Overall, the number increased from 1,632 in 2012 to 1,910 in 2013 (up 17 per cent).

The biggest rise was in the health sector - up from 210 the previous year to 338, a 61 per cent change. This was expected following the scandal at the Mid Staffordshire NHS Foundation Trust, which was exposed by a whistleblower.

Public Concern at Work said the more worrying trend was a big jump in the number of cases brought to it by people working in education, which rose from 243 in 2012 to 382 last year (57 per cent).

The organisation, which runs a free confidential advice line for workers, said many teachers had been left unsure who to approach when they saw something wrong at work.

Cathy James, chief executive of Public Concern at Work, said: “There has been a sharp rise in the number of concerns raised in the health and education sectors, this is something everyone should take very seriously. While it can be argued that an increase in the number of whistleblowers is a positive, these are core sectors dealing with young, vulnerable and infirm people and to see such a dramatic rise should act as a warning to regulators.”

She added: “In the health sector we did expect to see a rise in the number of concerns given the high profile cases which had been brought to light. However, the most concerning of the two is the rise in education as this indicates a worrying lack of oversight in the sector. Teachers are often confused about where to go in a rapidly changing sector. For example, for many of those working at academies, it has not been made sufficiently clear that local authorities remain responsible for safeguarding children. It is not clear at all who they are supposed to approach if they have financial concerns.”

Ms James expressed concern that in 63 per cent of the cases brought to it, the problems raised were either denied or ignored by employers and that in a third, whistleblowers were sacked. Only 10 per cent of concerns were resolved by employers and only six per cent of people seeking advice thought their workplace improved.

“We are making some progress in breaking the culture of silence, but what has followed is systematic refusal by employers to take those concerns seriously, creating a culture of denial,” she said.

A Department for Education spokesman said: “We have published clear guidance for maintained schools, academies, free schools and early years providers clearly setting out what the complaints procedures employers must put in place and how staff or members of the public can make a complaint in relation to any of these areas. All concerns raised are reviewed and where appropriate action is taken.”