The French government refused on the day before to give ground in its battle with unions over a reform of generous pensions for some workers, opening the way for a strike that could paralyse public transport for days.

Unions representing rail, public transport, electricity and gas workers have said they will hold a nationwide strike tomorrow, the second in a month, with some workers warning of staying indefinitely. Union leaders accused President Nicolas Sarkozy of intransigence and of making reform of the so-called ?special regimes? into a political battle of wills.

The pensions showdown is the biggest challenge Sarkozy has faced since taking office in May and his government fears its credibility would be destroyed if it gives into the unions. ?Our determination is not posturing, it?s a demand for justice and fairness,? Prime Minister Francois Fillon said in a newspaper interview. ?There is no other solution to save the pensions (system) other than reform. When one is carrying out one?s duty, one isn?t afraid,? he told Le Journal du Dimanche. Sarkozy was elected on a pledge to do away with the special regimes, which allow some state sector employees to retire after 37.5 years of work against 40 years for most other workers. The government wants everyone to retire after 40 years of contributions from 2012 and have told unions to negotiate with the companies involved to see how to implement the measure.

Unions seek just one negotiating table, with the government involved in the talks, but this demand has been rejected. ?The government has clearly chosen a show of force,? said Bernard Aubin, the secretary general of the rail arm of the CFTC union, which is viewed as a moderate labour group. ?There are all the ingredients for a very tough conflict.?

The government is hoping to split the union movement and one small train drivers organisation signed a pension deal for their members with the SNCF state railways on Friday meaning they will be the only one of eight rail unions working tomorrow. The other unions have said their strike is open-ended and some have indicated they want the stoppage to carry on until November 20 when civil servants and teachers have called a strike to protest about planned public sector job cuts. Adding to the probable transport chaos, student activists said they planned to block train stations around France today to denounce a government reform of the university system.

The reform, which encourages private sector financing in universities, was introduced in July and the government accused students of trying to cash in on the pensions dispute.