Teachers should be working an average 45-hour week, says a report commissioned by the government.

But this should remain a "target" rather than a fixed limit on hours, says the teachers' pay body for England and Wales.

Estelle Morris has rejected calls for a fixed 35-hour week as "potty"

The report's recommendations - which could become a blueprint for a deal in the dispute over teachers' workload - would represent an average 14% cut in working hours.

There should also be guaranteed time in the school week for marking and lesson preparation, says the report.

There are also calls for classroom assistants to take on non-teaching tasks, such as photocopying and administrative work.

And the report argues for a greater awareness of the impact of government initiatives on teachers' workload.

Doug McAvoy says the report is a "significant advance"

At present, teachers work an average of 52 hours a week, and the report says that this needs to be reduced to improve the "work-life balance".

Setting "targets" rather than fixed hours, the report calls for a reduction to 48 hours per week in two years and a further reduction to 45 hours after four years.

Both teachers' unions and the government are claiming support from the report's conclusions.

Unprofessional

The government says the report is a clear rejection of setting any fixed limit on hours.

The report concludes that a statutory limit on hours would be "unconvincing on practical grounds and unusual for professional people".

Any deal on workload will depend on Chancellor Gordon Brown in this summer's funding review

Education Secretary Estelle Morris, welcoming the report, says that it is "vital that teachers spend their time teaching, not doing tasks that can be done by others".

Teachers' unions, which are threatening industrial action in support of a 35-hour week, say that the report accepts the principle of a reduced week and protected time for lesson planning.

'Significant advance'

"The principles put forward offer a significant advance," said Doug McAvoy, general secretary of the National Union of Teachers.

Teachers should not have to do the ...

photocopying chasing absentees collecting money processing attendance figures exam timetables and results basic computer repairs stock-taking taking minutes at meetings arranging cover for absent teachers producing class lists and standard letters

And although the figure of a 35-hour week has been much canvassed, Mr McAvoy at this year's NUT conference made clear that this figure was open to negotiation.

But if the principle of a 45-hour week is adopted, it still remains unclear how such a reduction in hours and protected non-teaching time would be put into practice.

Schools are already struggling to find teachers - and the proposed reforms are likely to require even higher levels of staffing.

Guaranteeing time within the school week for lesson preparation could also raise difficulties for smaller primary schools, where there is little scope for flexibility in providing cover.

The government, downplaying any expectation of swift action, has stressed that these are long-term changes and that there is a long process ahead of adding detail to the principles.

The Shadow Education Secretary Damian Green said that the report highlighted how the government was contributing to an excessive workload for teachers.

"It is ludicrous that this year alone, the government has issued documents totalling 4,440 pages to schools, equal to 17 pages for each working day," said Mr Green.

Much will also depend on the levels of funding made available in the government's spending review.

The Liberal Democrat education spokesperson, Phil Willis, claimed the reforms would cost �1bn - and without money from the Chancellor the plans "will be little more than hot air".

The proposals from the School Teachers' Review Body will be open to consultation until 3rd July.