*Supply cut at fuel pipeline to Paris
*Truckers union calls drivers to join protests
*Police arrest dozens in student protests
Catherine Bremer -- Reuters
PARIS, Oct 15 (Reuters) - French refinery workers cut off a fuel pipeline to Paris on Friday as protesters piled on pressure to derail President Nicolas Sarkozy's unpopular pension reform.
Police broke up blockades at fuel depots in southern France but protesters blocked a terminal at Paris's Orly airport and truckers were set to join the fray as momentum built for a day of street rallies on Saturday.
A nationwide strike is planned on Tuesday, a day before the Senate is due to vote on a bill to make people work longer for their pensions.
The protests have become the biggest challenge facing the centre-right president, who is struggling with rock-bottom popularity ratings as he tries to appease financial markets by stemming a ballooning pension shortfall.