The new socialist mayor of Paris is risking the wrath of teachers by tackling the contentious timetable, to improve co-ordination of afterschool activities.

Particularly thorny for Mayor Bernard Delano is the arrangement of the school week. Traditionally schools have Wednesdays off and hold classes on Saturday mornings, a practice which originated to allow children time to learn their catechism - but which many families now dislike.

Repeated efforts at reorganisation by governments of the left and right have led to years of wrangling, resulting in variations across the country. These include keeping the status quo, working only one Saturday in two or three, switching lessons from Saturday to Wednesday mornings or, as a quarter of schools now do, introducing a four-day week with both Wednesdays and Saturdays free but with shorter holidays.

Although France’s education system is run centrally, local authorities have certain responsibilities for primary education including the provision of out-of-school activities. The co-ordination of these activities is the key reason why mayor Delano wants to reform the hours worked by Paris’s 9,324 elementary and nursery teachers and their 170,363 pupils, who currently attend on Saturdays.

At the end of November he called a conference for more than 1,200 representatives from teachers’ unions, school inspectors, politicians, city hall officials, parents and chronobiologists (experts on biological rhythms) to try to reach an agreement.

It was a vain hope, with a quarter of teachers striking for a day and schools closed in protest against the “sham consultation”, rightly assuming that the mayor would opt for the transfer of Saturday’s classes to Wednesday. While this might satisfy parents, many teachers prefer the traditional system and fear their jobs are at risk from encroaching out-of-school activities.

Rene Blanchet, Paris’s chief education officer, is due to publish detailed proposals in January. As well as supporting Mr Delano , he favours seven weeks school alternating with two weeks holiday, a system introduced some years ago, but abandoned after ski resorts and tourism companies complained it would disrupt business.