Teachers have threatened industrial action over plans to reorganise the school year into five terms and end the long summer holiday.

Delegates at the National Association of Schoolmasters/Union of Women Teachers (NASUWT) conference in Eastbourne backed an emergency motion supporting industrial action by members in areas which attempt to modify the school year.

The NASUWT's leadership signalled its opposition to the concept of the five-term year, arguing that the removal of "the last perk of teaching" - the long summer break - would make it even harder to encourage graduates to become teachers.

A history teacher from Lancashire, Sarah Jane Millington, derided parents who complained that their children got bored during the long summer holiday.

"I'm not a babysitter, childminder or prison warder," says Sarah Jane Millington.

"I'm not a babysitter, childminder or prison warder," she said. "You all knew before the conception about the summer holiday."

East Sussex is one of six local education authorities in England which is proposing to introduce a five-term year.

The changes in the county, which are scheduled to be introduced from next year, would see children and their teachers return to school after about a month. They would get extra holidays at other times during the year.

Steve Hill, a teacher from East Sussex who proposed the emergency motion, said supporters of the reform argued that children fell behind during the six-week summer holiday.

But he insisted: "The whole issue of learning loss is a nonsense, a red herring dragged up to rationalise an illogical decision. The length of the holiday has nothing to do with children's academic performance.

Teachers say extra hours will not mean improved pupil performance

"Look at Europe, look at the private sector - longer breaks than we get in summer and we're constantly being told that they perform better than we do."

Supporters of change argue that the current school year is a throwback to days when lessons were arranged around farm harvest times, but the NASUWT's leadership says the current school year is designed to fit in with university academic years, and that any change would throw timetables for GCSE and other exams into chaos.

The union's General Secretary, Nigel de Gruchy, warned that moves towards a five-term year could lead to industrial action.

"The one last perk of teaching is the long summer holiday, and local authorities had better keep it because I don't think they can afford to compensate teachers for losing it," he told journalists.

Teachers dispute that children fall back in the summer holiday

Mr de Gruchy added that the proposed changes could interfere with family holidays and lead to more children taking time off school to go away with their parents.

But the Local Government Association's Education Chairman, Graham Lane, a strong supporter of reforming the school year, said teachers were the only group of workers in the country to demand a long summer holiday.

"There's no evidence they need a longer holiday," he said. "We must consider the effects on children."

The other education authorities proposing a five-term year are the London boroughs of Newham and Croydon, as well as Bradford, Bristol and Thurrock. There are also rumours that the five-term year could be introduced across London as a first step to changing the school year throughout England.

A secondary school in Essex has already decided to switch to a five-term year and abolish the long summer holiday.

Pupils at the Greensward School in Hockley will attend lessons for five eight-week terms from next January. During the year, they will have four two-week holidays and a month-long summer break.