For the second time in three days, students . . . this time joined by unions and employees . . . were using marches to press the conservative government to withdraw the measure, which could take effect in April.

"We are not disposable. We deserve better, " said Aurelie Silan, a 20-year-old student who joined the massive protest in Paris. She held aloft a banner mocking prime minister Dominique de Villepin, just one sign of the mounting pressure he faces. "Aren't we the future of France?" Silan asked.

In Toulouse, up to 33,000 people marched against the jobs plan to cries of "No to a government that makes students (and) workers fodder for employers". In Lyon, police put the number of demonstrators at 10,000, but organisers said 25,000 participated.

The plan, known as the 'new jobs contract', is meant to increase employment among less privileged youths by making the labour market more flexible. However, it does away with classic protections and students fear it will leave youths in more precarious situations and eat away at measures that protect employees.

Organisers said 160 marches were planned nationwide, with the largest expected in Paris, where massive and boisterous crowds kicked off their protest on a sunny afternoon.

Student demonstrators have paralysed 16 universities and disrupted classes at 35 others, the education ministry said.

That and the violence that has accompanied previous demonstrations has put intense pressure on Villepin to act. On Friday night, a group of university presidents met Villepin and called on him to withdraw the jobs plan for six months to allow for debate.

President Jacques Chirac called for immediate negotiations but he stood by the law, calling it "an important element in the policy of fighting unemployment".