On the corner of a steep, narrow Marseille street this week, the opening chords of Eye of the Tiger thundered from giant speakers as 100 or so women in pink and white overalls with fists raised marched from the Force Ouvrière union head office. Some carried posters showing themselves decrepit and grey-haired, trying in vain to usher children to the dining table.

For weeks a mass rebellion by the city's dinner ladies, affectionately known as tatas, has forced more than half of the city's nursery and primary school canteens to close. These women in white overalls and slip-on plastic shoes, joined by their pink-clad counterparts in the city's creches, have downed soup ladles and cheese knives and taken to the streets in protest at Nicolas Sarkozy's pension reforms.

Arabelle Lauzat, 45, a head dinner lady in a primary school who has been working in school canteens for 15 years, finds the job physically exhausting. "There's a lot of heavy lifting, quite an intense work rhythm and a lot of noise," she said. "We've all got health problems: bad backs, slipped discs, ear problems. It's a profession you love, but it wears your body out."

She fears that Sarkozy's plans to raise the minimum pension age from 60 to 62 and full pension age from 65 to 67 will require them to work long after they are physically able to deal with children.

"If we're forced to work until we're 67 you're going to see a lot of workplace accidents," she said. "Already we've seen falls down stairs. There are cases of depression, because there's more and more work for fewer staff and we're under a strict hierarchy. It's not an easy life. You get home at night and you don't want to cook, you don't want to clear up. You're shattered."

Amid the refinery strikes, oil depot picket lines, petrol stations running dry and sixth formers blockading classrooms across France, the Marseille dinner ladies have become the symbol of French women's rebellion against Sarkozy's retirement reform. Aged on average between 35 and 50, the majority are single mothers, struggling on small wages to raise their own children and pay rising rents. Many took breaks from work to have children, leaving gaps in their state pension contributions.

Sarkozy has already made a limited concession to women, allowing those born in the early 1950s who brought up three or more children to collect full pension at 65, but that affects only a limited number of women and the tatas say it's not enough. They vow to keep up the blockade of school canteens until the government withdraws its whole pension reform.

The dinner ladies, and their creche counterparts, reheat the strictly nutrition-controlled main courses delivered to school, and add three more courses: starter, cheese and healthy desserts. But most also supervise the children while they are washing their hands and eating, change infants and clean school rooms.

"Most are on duty from 6.30am for nine hours a day, with a 30-minute break when they must stay on site," said Joseline Cozzolino of the UNSA union.

"There is one agent to 30 children in nurseries and one to 60 in primary schools, feeding children and doing all the cleaning up. They earn €1,200 a month and are often raising families alone. Of 314 school canteens in the city, we've seen peaks of 130 to 150 closed. On Monday this week 230 were closed. We're not going to give up."

Many headteachers and teachers have also staged strike days in support, with schools closing across the city.

Betty Ferrier, 56, has worked feeding babies and young children for 20 years. "We're totally passionate about our jobs," she said. "To see a tiny baby come into the creche at three months old and see them all the way through until they leave at three is amazing. But we're already stretched – our bodies won't hold out until 67. I spend most of my time bent-double to the height of children's furniture. We've all got bad backs and take anti-inflammatories or other medication.

"A lot of people in our profession are dangerously close to the poverty line – some can barely pay their rent. I've heard of people forced to sleep in their cars. We're all putting our hands in our pockets to help each other as we're not paid for the hours we strike. Already colleagues who have retired on state pensions of €700 a month can barely pay rent and food bills."

Some parents had initially been outraged that schools were shut. "But we explained that their children's future safety was at stake," she said.

Nathalie du Tola, 40, a nursery dinner lady, has been on strike since September 23. "I'm losing pay as the strike days tick by," she said. "But I get goosebumps when I'm standing in a crowd of demonstrators with so many people supporting us. There's no way we'll give up now. We'll keep going till the end."