A planned open-ended strike against the SNCF would be like putting a gun to the company's head and could cost it 20 million EUR(US$29 million) per day.
The strike, which is to begin Tuesday evening, would be the second serious transport disruption to hit France since October, when transit workers staged a wave of walkouts to protest plans by President Nicolas Sarkozy to cut special retirement benefits for some state workers.
SNCF General Director Guillaume Pepy said the walkout would be like putting a "pistol to the temple," and he warned of the possible monetary and social costs.
There is "really the risk of a very serious disturbance for passengers who already suffered through (last month's) strike," Pepy told RTL radio on Friday. He said a massive walkout could cost the company about 20 million EUR(US$29 million) per day.
With all but one union refusing the company's calls for negotiations, railway officials have tried to communicate directly with the company's 160,000 employees.
SNCF President Anne-Marie Idrac sent an e-mail Thursday to SNCF employees to try to dissuade them from walking out.
"The planned strike, costly for those who will take part in it, does not bring anything positive to the company or the railroads," the e-mail said.
Education Minister Valerie Pecresse also tried Friday to dissuade other French protesters - university students disrupting classes at about 10 campuses around the country.
The students were protesting a new law aimed at making France's public universities more market-friendly by giving them the right to raise tuition and accept private donations.
Pecresse told France Info radio she "vigorously condemns these disruptions" and called on student representatives to enter into talks with the government.
After a Paris march Thursday, student protesters briefly stopped traffic at the Gare du Nord train station. Some 300 demonstrators poured into the station, blocking traffic for about an hour before they were ousted by police, a Paris police official said. No violent incidents were reported, the official said.
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