France's retirement protest strikes turned violent today as youths clashed with riot police in cities across the country.
Meanwhile flights were disrupted, public transport thrown into chaos and there was growing alarm among motorists over fuel shortages with hundreds of filling stations running dry.
President Nicolas Sarkozy, who has staked his reputation on bringing in tough economic measures, including raising the retirement age from 60 to 62, pledged to crack down on "troublemakers" and said he would ensure that "public order is guaranteed."
More than 200 protests and one-day strikes by workers in sectors across the French economy were held around the country.
Initial estimates from the SNCF national railway operator and the Education Ministry suggested the number of public sector strikers was diminishing after week of disruptions.
In many cities, protesters were being joined by youths who appeared to be seizing an opportunity to lash out at police.
At a school in the Paris suburb of Nanterre, closed because of earlier violence, a few hundred youths started throwing stones from a bridge at police, who responded with tear gas.
Nanterre has often seen student protests in past years and the latest clashes were reminiscent of 2005 riots that spread through poor housing projects nationwide with large, disenfranchised immigrant populations.
At the Place de la Republique in Paris, youths pelted riot police with projectiles and started fires. Similar skirmishes broke out in other cities.
It was the sixth national day of demonstrations over the planned pension reform since early September. Union leaders have vowed to keep up the pressure until the government scraps the unpopular plan, saying retirement at 60 is a fundamental social right.
Mr Sarkozy called the reform his "duty" as a head of state and said it must go through to save France's generous but money-losing pension system.
He has stressed that 62 is among the lowest retirement ages in Europe, the French are living much longer and the pension system is losing money.
The measure is expected to pass a vote in the Senate this week. Originally due to tomorrow, it has been pushed back until later in the week so MPs have the time to examine hundreds of amendments brought by opposition Socialists and others.
The protests in France come as countries across Europe are cutting spending and raising taxes to bring down record deficits and debts from the worst recession in 70 years.
The DGAC civil aviation authority said up to half of flights today out of Paris' Orly airport would be scrapped, and a third of flights out of other French airports, including the country's largest, Charles de Gaulle, serving Paris, would be cancelled.
Most were short- and medium-haul domestic and inter-European flights. The walkout by air traffic controllers was expected to last one day, with flights expected to return to normal tomorrow.
Strikes by oil refinery workers have sparked fuel shortages that forced at least 1,000 filling stations to close. Others saw large crowds.
At one on the south of Paris today the queue snaked for hundreds of yards and some drivers carried petrol cans to stock up with.
Mr Sarkozy said such shortages "cannot exist in a democracy."
"There are people who want to work, the immense majority, and they cannot be deprived of petrol," he insisted.
Police in the north-western town of Grand-Quevilly moved protesters blocking a fuel depot which had been completely sealed off.
Truckers have joined the protest, creating huge tailbacks by driving at a snail's pace on roads.
About 20 truckers blocked an oil depot in Nanterre west of Paris operated by Total, turning away fellow truckers coming to fill up.
Students entered the fray last week, blockading high schools and staging protests that have occasionally degenerated into clashes with police.
With disruptions on the national railway entering their eighth consecutive day, many commuters' patience was beginning to wear thin. Only about one in two trains were running on some of the Paris Metro lines.
Caroline Mesnard, a 29-year-old teacher said she expected her commute to take about twice as long as usual - as it has since last Tuesday's start of the open-ended strike on France's trains.
"All I can say is that after eight days, it's beginning to get a bit tiresome," she said. "I'm really tired, but there's nothing to be done but hang on and wait for this to end."
In Marseille, strikes by binmen have left heaps of rubbish piled along pavements.