* Refinery workers stay on strike, truckers slow roads
* Government says will not permit industry blockades
* Petrol pumps run dry, police break up youth crowds
(Adds Sarkozy comment)
By Brian Love
PARIS, Oct 18 (Reuters) - French truck drivers staged go-slow operations on highways, trains were cancelled and petrol stations ran out of fuel on Monday as strikers dug in ahead of a Senate vote this week on an unpopular pension overhaul.
Wider strikes will hit everything from air travel to mail on Tuesday when unions opposed to President Nicolas Sarkozy's plan to raise the retirement age have called for one more en masse street protest against the unpopular pension bill.
With a final Senate vote on the legislation expected from Wednesday, this could be a make-or-break week for Sarkozy.
The centre-right government, which has stood firm through months of anti-pension reform protests, assured the public infrastructure would not freeze up despite a week-long strike at refineries that has dried up supplies at hundreds of France's roughly 12,500 petrol stations.
"The situation is critical," a spokeswoman at Exxon Mobil said. "Anyone looking for diesel in the Paris and Nantes (Western France) regions will have problems."
Sarkozy, in the northern seaside town of Deauville for talks with the leaders of Germany and Russia, said he would not back down. "The reform is essential and France is committed to it and will go ahead with it just as our German partners did," he told reporters after meeting German Chancellor Angela Merkel.
Only 13 percent of rail workers kept up a week-long strike on Monday but workers at France's 12 refineries were in their seventh day of a strike and protesters blocked access at many fuel distribution depots around the country.
The UFIP oil industry lobby has said France could see serious fuel supply problems by mid-week, meaning the government may have to tap emergency reserves. The DGAC aviation authority urged airlines to reduce flights to Paris's Orly airport by 50 percent and to all other airports by 30 percent on Tuesday.
Tuesday will be the sixth major work stoppage and street demonstration called by labour union confederations since June but the unrest has intensified since last week when unions at railways and refineries began open-ended industrial action, joined now by truck drivers and delivery workers.
GOVERNMENT REASSURES, FUEL STATIONS DISRUPTED
Government ministers stressed the country had plenty of fuel and that airports in particular have ample supply.
"The government is in control," Industry Minister Christian Estrosi said. "There will be no blockade for companies, no blockade for transport and no blockade for road users."
As many as 1,800 service stations have run short of fuel in recent days. A body representing supermarket fuel stations said 500-1,000 were hit on Monday. Total said 400 of its stations had been affected and Esso reported a similar toll.
At an empty station on Paris's Champs Elysees avenue, manager Paula said she spent much of her morning trying to stop drivers unhooking fuel pumps. "It's madness, we're submerged," she said.
The International Energy Agency, which overlooks strategic oil supplies in OECD countries, said that France as of Friday had 98 days of fuel between industry reserves and government reserves and the country had started to tap the industry stocks.
A majority of French people -- 71 percent in one poll -- back protests over the plan to raise the minimum and the full retirement ages by two years to 62 and 67 respectively, a move the government says is vital to stem a soaring pension deficit.
Jerome Sainte-Marie of CSA pollsters said that this showed the price the government would pay if it stayed the course but that presidential and legislative elections were some time off.
"It's not certain this political cost will last until 2012," he told Le Parisien daily.
The bill's main points have passed through both houses of parliament. The Senate will now vote on the entire package, which the lower house has approved. The Senate vote risked slipping by a day or more beyond Wednesday due to slow progress through 1,000 amendments tabled by the opposition.
Analysts anticipate a yes vote in the Senate after which the government hopes a vote by a committee representing both houses of parliament will take place by end-October.
Truck drivers used vans to slow traffic on motorways around Paris and cities like Lille, Rennes and Lyon, but were not using fleets of large trucks to block roads.
Prime Minister Francois Fillon has warned that people blocking fuel depots were breaking the law.
TV stations broadcast footage of workers at the Grandpuits refinery saying they had been "requisitioned" under government orders to go to work or risk jail but that they could not work because co-workers had formed human chains at the site.
The government is not threatening more police action but unions are wary after police intervened last week at some depots.
Riot police used teargas and rubber pellet guns in the Paris suburb of Nanterre to break up a crowd of youths who set fire to cars near an anti-reform protest by secondary school students. They intervened for similar reasons in the city of Lyon.
Sarkozy was greeted by 100 or so supporters as he arrived in the northern seaside town of Deauville for talks with his German and Russian counterparts Angela Merkel and Dmitry Medvedev.
(Additional reporting by Catherine Bremer, Valerie Parent, Muriel Boselli, Tim Hepher and John Irish; Editing by Michael Roddy)