Protesters clashed with police in Paris and western France on Thursday as workers and students across the country made a new push for the withdrawal of a hotly contested labour bill.
Demonstrations as well as work stoppages, notably in the aviation and public transport sectors, are planned across France in the latest actions in a protest wave that began two months ago.
Opponents to the reform, billed as an effort to lower France's stubborn 10 percent unemployment, say it will threaten cherished workers' rights and deepen job insecurity for young people.
Clashes broke out in the western city of Nantes, with police firing tear gas at protesters throwing stones, paint and smoke bombs.
In Paris, police said scuffles pitting more than 100 masked youths against security forces left one policeman injured.
In the northern port of Le Havre, hundreds of strikers, mainly dockworkers, blocked all the main access routes into the city with barricades of burning tyres, the BFMTV rolling news channel reported.
Meanwhile civil aviation authorities said passengers at Paris's Orly could expect one in five flights to be cancelled, while delays were expected at Charles de Gaulle airport.
The unions and student organisations plan to pile on the pressure with further protests on Sunday to mark the May Day labour holiday, as well as next Tuesday, when parliament begins debating the bill.
Christophe Sirugue, the Socialist lawmaker who is present the bill to parliament after it was reviewed in committee, said Thursday that several points still needed "clarification" during the debate but that he expected the bill to pass.
Among the remaining issues are measures to make it easier to lay off workers in lean times, and whether employers should still be allowed to shed workers if conditions are depressed in their overseas operations and not just in France.
Another is a proposed surtax on short-term contracts aimed at getting employers to hire more people on permanent contracts, Sirugue told business reporters.
Protests against the reform kicked off on March 9, culminating in massive demonstrations on March 31 that brought 390,000 people onto the streets, according to an official count. Organisers put the number at 1.2 million.
The protests spawned a new youth-led movement called "Nuit Debout" (Up All Night), which has seen advocates of a broad spectrum of causes gather in city squares at night for the past four weeks to demand change, though attendance has been dwindling in recent days.
With little more than a year left in his mandate, France's deeply unpopular President Francois Hollande has been banking on the labour reform as a standout initiative with which to defend his record.
But in the face of the protests his Socialist government has watered down the labour reforms -- only to anger bosses while failing to assuage workers.