Teachers’ working hours are increasing, with “unsustainable” workloads jeopardising the quality of education for millions of students worldwide, teaching unions have warned.

After a report published last week revealed that teachers in English schools were routinely working almost 60 hours a week, international education leaders warned that the trend was being seen internationally because of school budget cuts.

In June, results from the Teaching And Learning International Survey will be published for the first time in six years, including information on how much time teachers in more than 30 countries spend on tasks such as lesson planning and marking, as well as teaching.

Fred van Leeuwen, general secretary of global teaching union federation Education International, told TES he expected this year’s figures to show that reductions in school budgets were leading teachers to work longer hours than ever before.

“We have received reports from education unions around the world that teachers’ working hours are on the rise, as is the number of teachers unable to cope with the resulting increasing stress levels,” he said. “While budgets are being consolidated or reduced, teachers are requested to take on more administrative, managerial or counselling tasks instead of being allowed to concentrate on their core duty, which is to teach students.”

The report on teacher workload in England, published by the Department for Education, finds that primary school teachers work 59.3 hours a week on average, up from 50.9 hours in 2010. The survey also shows that teachers in maintained secondary schools and academies work just over 55 hours a week, rising to 63.3 hours for school leaders - six hours more than in 2010.

The DfE said the figures were not comparable because of a change in methodology, but Christine Blower, general secretary of the NUT teaching union, said the number of hours that teachers were having to work was “simply unsustainable”.

“Many teachers feel totally overwhelmed, and it is hardly surprising that two in five leave the profession after their first five years in the job and morale is at an all-time low,” she added. “Our children deserve enthusiastic, energetic teachers, not overworked and stressed ones.”

The most recent national school workforce survey in the US, carried out in 2012 by the Bill and Melinda Gates Foundation and publishing firm Scholastic, found that teachers across all schools were working an average of 53 hours a week.

Rob Weil, director of field programmes and educational issues at the American Federation of Teachers, said that many US teachers were given no time during the day for lesson planning or marking. An increased focus on testing and accountability in many districts in the past two years had led to more administrative tasks being “dropped” on teachers, he added.

Discontent is even spreading among teachers in Finland, a perennial high performer in the Programme for International Student Assessment (Pisa) league tables. Mika Visnen, economics expert for Finnish education union Opetusalan Ammattijrjest, told TES that there had been an increase in complaints from members about long working hours.

“The consequences of this are that teachers have a strong, constant fatigue and [increased] stress,” he said.

In France, official government figures published last year revealed that teachers’ average working weeks were between 39 and 43 hours long, depending on the type of school. This was an increase of one hour since the previous report in 2008, a rise that the SNES-FSU union attributed to teachers having to mark more homework and attend extra meetings.

And it is not just teachers in Western nations who are being affected: the Organisation for Economic Cooperation and Development last year reported that teachers in Argentinian upper secondary schools spent 1,448 hours a year teaching, not including lesson planning, marking and other tasks. This was more than double the international average of 664, and almost four times the 369 hours of teaching required in Denmark.

Mr van Leeuwen said the problem was caused by inadequate teacher recruitment and training in some developing nations where, he warned, “double shifts are no longer the exception”.

“If governments continue to fail to invest in teachers, in their training, in their professional development and in their working conditions, it will no longer be an attractive [profession],” he added. “This, inevitably, will affect education quality.”