From Tuesday evening the country's train network is set for major disruption as trade unions launch an open-ended strike against plans to end historic pensions privileges enjoyed by some 500,000 rail and energy employees.

The strike, which will also bring the Paris metro to a near standstill, could extend at least to the week's end in what is increasingly seen as a trial of strength between unions and Sarkozy's centre-right government.

With other protests by students, lawyers and civil servants also brewing -- and amid growing public disquiet about the cost of living -- commentators said the president could be set for the kind of epoch-making showdown pioneered by British Prime Minister Margaret Thatcher in the early 1980s.

"Mrs Thatcher warned that things would be hard. Some found her reforms odious, but she had the courage to be unpopular. The question is, does Sarkozy have the same courage to be unpopular?" asked Eric Brunet, author of "Being Rightwing -- a French taboo."

Sarkozy can find comfort in a survey published Monday showing 55 percent of French believe Wednesday's strike is "not justified."

The findings by the BVA polling institute show French opposition has mounted two points since the previous transportation strike October 18, when a similar poll was taken.

The last time a government tried to reform the so-called "special" pensions systems was in 1995, when three weeks of strikes and demonstrations forced the government under newly-elected president Jacques Chirac into a humiliating climbdown.

Monday's BVA poll showed some 68 percent of French fear the latest pension reform efforts risk unleashing the same paralysing strikes as in 1995.

But this time ministers say the situation is different, because the climate of opinion has changed -- a majority supports the pensions reform -- and because Sarkozy clearly spelled out his intentions in his May election manifesto.

"What is at stake is people's faith in politics," Labour Minister Xavier Bertrand said Monday.

The "special" systems are enjoyed by 16 separate categories of workers, who can retire after 37.5 years instead of 40 and have their pensions calculated on the basis of final salary rather than an average over their whole career.

Invoking social equity, Sarkozy has moved to bring the "special" regimes in line with the rest of the population -- and the ensuing confrontation has become a symbolic battle of wills over the whole of his reform agenda.

The left-wing opposition accused Sarkozy of actively seeking a confrontation to deal a defeat to the unions.

"Rather than using the remaining time to seek a way out from the conflict, the government and the president want maximum tension," said Socialist Party national secretary Bruno Le Roux.

The atmosphere has been soured further by protests from students complaining about a university reform law, and from lawyers and magistrates angry at moves by Justice Minister Rachida Dati to reorganise the local courts system.

On November 20 a 24-hour strike has been called by civil servants against plans to cut the state payroll, and some union organisers hope this week's rail strikes can be extended so that the anti-government movements become one.

The rail strike, which kicks in at 8.00 pm (1900 GMT) Tuesday, is the second in less than a month, but the last one was only for a day. In Paris commuters were readying themselves for the inevitable chaos, with sports shops reporting a run on bicycles.