Hundreds of thousands of civil servants have joined striking transport and energy workers as France is paralysed by a second week of industrial action.
Teachers, postal workers, air traffic controllers and hospital staff are holding a 24-hour stoppage over planned job cuts and higher wage demands.
Students are continuing to demonstrate over university funding plans.
Many thousands joined street protests in Paris, Rouen, Strasbourg, Marseille, Grenoble, Lyon and other cities.
It could end up as the biggest show of defiance at President Nicolas Sarkozy's reform plans since his election in May.
The latest nationwide stoppage left many schools closed, hospitals providing a reduced service and newsagents without newspapers.
The French capital's two airports and Marseille airport in the south suffered delays and cancellations.
French energy workers, who began a third 24-hour strike on Monday night, have cut nearly 9% of capacity at nuclear plants, union officials said.
And rail and bus workers are on their seventh day of an indefinite stoppage against planned pension cuts.
Finance Minister Christine Lagarde said the dispute was costing France up to 400m euros (£290m) a day.
Half of the country's high-speed TGV trains were operating on Tuesday, while in Paris only one metro train in three was in service and less than half of buses were expected to run.
State rail operator SNCF, which is due to hold talks with transport unions on Wednesday, says the number of its workers on strike had fallen since last week.
Teachers, civil servants oppose job cuts and want more pay
Newspaper distributors angry at planned restructuring
Transport workers on strike for a week over pension reforms
Students protest at changes they say could exclude poor
But with traffic gridlock on the capital's roads on Tuesday morning, the stoppage still caused havoc for commuters.
BBC world affairs correspondent Nick Childs says the French president has been keeping a low profile, perhaps to test the public mood.
Mr Sarkozy may wish to avoid a counter-productive confrontation, but his public absence risks being construed as a sign of weakness, our correspondent says.
Opinion polls suggest voters back the French leader's plans to reform "special" pensions which allow transport and utility workers to retire early, but a majority sympathises with civil servant grievances.
Analysts say Mr Sarkozy is attempting to succeed where his predecessor Jacques Chirac failed, by standing firm against the strikers and completing his reforms.
Walking to work in the centre of Paris, commuter Guy Cousserant, 56, told Reuters: "A small group of people are holding the country hostage. It's lamentable, very annoying."
But one woman in the capital told AP news agency: "The civil servants' purchasing power has dramatically lowered. I think they have the right to go on strike."
The education ministry said 40% of teachers had walked out but union officials said the figure was more like 60%.
Eight unions representing 5.2 million state employees - around a quarter of the entire workforce - say their spending power has fallen 6% since 2000, though the government disputes that figure.
'SPECIAL' PENSIONS SYSTEM
Benefits 1.6m workers, including 1.1m retirees
Applies in 16 sectors, of which rail and utilities employees make up 360,000 people
Account for 6% of total state pension payments
Shortfall costs state 5bn euros (£3.5bn; $6.9bn) a year
Some workers can retire on full pensions aged 50
Awarded to Paris Opera House workers in 1698 by Louis XIV
They also oppose plans to cut 23,000 jobs in 2008, half in education.
Students are continuing to block access to campus buildings in half of the country's 85 universities.
They have been protesting since the start of November over plans to let faculties pursue non-government funding.
Prime Minister Francois Fillon said on Monday the government was ready to talk with unions but insisted it would not budge on plans to overhaul the French economy.