Cancelled trains, packed roads, frazzled nerves: Travellers scrambled across France on Friday to begin Christmas vacations upended by a weeks-long transport strike over a pensions overhaul that unions have vowed to defeat.

Hopes of a holiday truce were dashed after talks between the government and union leaders this week failed to ease the standoff, with train operator SNCF warning of massive cancellations ahead of the holidays.

Many stranded travellers turned to car rental agencies or sharing platforms, but the last-minute surge in demand meant vehicles were hard to come by.

"We've seen twice as many requests in some regions," mainly Paris and southwest France, said Robert Ostermann, France director for Europcar.

Trying to catch one of the few trains running
Trying to catch one of the few trains running AFP / Martin Bureau

Taxi companies in Paris had already stopped taking Friday reservations early this week as many metro lines remain shut, while Twitter is awash with irate Uber users forced to pay two to three times normal rates.

Others booked trips on buses, whose drivers have been allowed to stay behind the wheel longer until December 24 to cope with an "emergency situation," according to a government decree published Wednesday.

Prime Minister Edouard Philippe said Thursday that talks with unions had nonetheless made progress, and called on unions to lift the strike "so that millions of French can join their families for the end of this year".

Although the moderate UNSA union agreed, the hard-line CGT and Force Ouvrier unions said they would not let up.

"It's time for the government to realise that this project is a serious mistake," FO chief Yves Veyrier told France 2 television on Friday.

Paris braces for Christmas holiday travel chaos amid pensions strike
Paris braces for Christmas holiday travel chaos amid pensions strike AFPTV / Fabien NOVIAL

President Emmanuel Macron wants to forge the country's 42 separate pension regimes into a single points-based system, saying it would be fairer and more transparent.

That would do away with legacy schemes that offer early retirement and other advantages to mainly public-sector workers, not least train drivers who can retire as early as 52.

But while some unions support a single system, almost all reject a new "pivot age" of 64 -- beyond the legal retirement age of 62 -- which workers would have to reach in order to get a full pension.

They are hoping for a repeat of 1995, when the government backed down on pension reform after three weeks of metro and rail stoppages just before Christmas.

An Ifop poll released Thursday found six out of 10 respondents oppose the "pivot age" and more than half have sympathy for the strike despite the daily transport misery brought to bear on millions.

The protest is taking a heavy toll on businesses, especially retail during one of the busiest periods of the year, with industry associations reporting turnover declines of 30 to 60 percent from a year earlier.

Junior Economy Minister Agnes Pannier-Runacher has urged people to patronise local businesses during the crucial holiday season, saying "it's time to give them a hand."