Paris — France has effectively buried the country’s much-derided 35-hour week a decade after the Socialists introduced the flagship reform, following a Senate vote late Wednesday.

The bill was opposed by the opposition Socialists, but approved by the majority of UMP senators loyal to President Sarkozy, who has long blamed France’s short working week for many of its economic ills.

The new law — due to come into force in September — will empower companies to strike individual deals with unions or employees over working hours and overtime.

In theory, it could allow companies to demand staff work a maximum of 235 days a year, instead of the current maximum of 218, leaving 52 weekends, 25 days’ holiday, and the May 1 Labor Day holiday as guaranteed non-working days.

“At last we are leaving the 35-hour week,” declared Xavier Bertrand, the labor minister, shortly before the Senate vote.

Greens senator Jacque Muller called it “a regression without precedent since 1936.”

Mr. Sarkozy has been gunning for the changes since he came into power last year, as part of his electoral pledge to allow the French to “work more to earn more.”

With France now Europe’s champion holidaymakers with 37 days of paid leave a year — Italy is second with 33 days, while Britain trails with 26 days holiday a year — the president insists the country needs to regain the will to work.

But he has shied away from scrapping the 35-hour week altogether, conscious of its popularity among French workers and the boost that overtime work provides to consumer purchasing power, as it is not subject to income tax.

As a result, his reform maintains the baseline working week at 35 hours, although in reality most employees will work more.

Unions believe the new measures will affect small to mid-size companies first, where it is likely to be easier to negotiate enterprise-level deals. Changes to bigger companies, where negotiations over the 35-hour week proved long and costly, are likely to come later.