* New truckers' action Sunday evening, rail strikes Monday
* Panic buying over refinery strikes dries up petrol pumps
* Senate due to vote Wednesday on pension bill
* Fresh street protest on Tuesday to keep up pressure
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By Catherine Bremer
PARIS, Oct 17 (Reuters) - French truck drivers said they would block key roads from Sunday evening and rail unions announced new strikes from Monday, putting fresh pressure on President Nicolas Sarkozy over his unpopular pension reform.
New action by truckers and rail workers, continuing strikes by refinery workers and the threat of more street marches in the drive to force Sarkozy to scrap the reform before a crucial Senate vote, make this a make-or-break week for him.
Sarkozy has vowed not to give in throughout months of opposition to his plan to raise the retirement age and rein in a ballooning pension deficit. The powerful unions, which have a history of crushing reform, have vowed to match his resolve.
"If we do nothing ... the system will explode," Interior Minister Brice Hortefeux told LCI television, as the government kept up its appeal to a public that feels it is being unfairly punished for failures in the social security system.
Petrol pumps are drying up, truckers said they would block key roads from Sunday evening, and after a day of disrupted trains, rail unions agreed new strikes on Monday that could halt two-thirds of regular trains and half the express TGV services.
A fresh nationwide march against the pension reform -- which would raise the minimum and full retirement ages by two years to 62 and 67 respectively -- was set for Tuesday, testing Sarkozy's determination to stand by a key policy.
"The right to strike is not the right to prevent access to a fuel depot. This is an illegal action," Prime Minister Francois Fillon said on TF1.
"I will not let the country be blocked. I will not let the French economy be choked by a blockade of fuel supplies," he added.
Panic-buying by motorists sucked dry petrol pumps across France, though many hoped for fresh deliveries on Monday. Oil company Total said 350 to 400 of its petrol stations were suffering supply disruptions.
The UFIP oil industry lobby has warned that strikes running since Tuesday at all France's 12 refineries could cause serious fuel supply problems by mid-week, meaning the government may have to look at tapping its emergency reserves.
PETROL STATIONS CLOSED
Around Paris on Sunday, closed petrol stations posted signs saying "Fuel Sold Out". Others were reported to be raising the price of the fuel they had left. Economy Minister Christine Lagarde said that anyone inflating prices would be punished.
Shortages could hit transport much harder if truckers manage to clog roads on Sunday night and Monday, stopping fuel trucks, which themselves need fuel to run, getting through.
Fears that Roissy Charles de Gaulle international airport could run out of fuel in the next 48 hours were dispelled by Transport Minister Dominique Bussereau, who told Europe 1 radio a disrupted supply pipeline to the airport was working again.
"There is no concern about Roissy. We can feed it (with fuel) for an unlimited period of time," he said.
Most of France's fuel depots, located mainly outside refineries, have a couple of weeks' supply, but depots in southwestern France are already depleted because a three-week unrelated strike at a major oil port near Marseille has hit supplies of crude to refineries in the area.
The transport chaos could spur more protesters onto the street on Tuesday when unions plan a last-ditch nationwide demonstration against Sarkozy's bill a day before the Senate is due to vote on it. It could pass quickly into law after that.
Turnout at nationwide marches on Saturday was lower than at previous rallies, according to the government, which read that as a sign its message was getting through. The unions said up to 3 million people had taken part, but police counted 825,000.
"I think we're clearly at a crossroads. What I hope is that reason will prevail," Agriculture Minister Bruno Le Maire told Europe 1 radio.
Unions say they will not give up until the government drops the bill and invites them to have a say in a pension overhaul.
They believe new street protests, the latest in a series since the summer, will have more clout if combined with fuel shortages, cancelled trains and disruption caused by truckers.
Truck drivers are the big guns of French protests because of their ability to cripple major highways and stop the movement of vital goods like food. (Additional reporting by Nina Sovich and Anthony Paone, editing by Jon Boyle)