France hit by strikes over pension reform

Trains have ground to a halt in France, schools were shut and businesses disrupted as workers walked off their jobs in an attempt to derail a planned pension reform that would see the retirement age pushed up by two years to 64.

The nationwide day of strikes and protests on Thursday is a major test for President Emmanuel Macron, who says his flagship reform is vital to ensure the pension system does not go bust.

Opinion polls show French voters overwhelmingly reject his plan to make them work longer.

The challenge for unions, which are far less powerful in France than they used to be, is whether they can transform that opposition to the reform - and anger with a cost-of-living crisis - into a mass social protest that would last beyond Thursday and eventually get the government to back-track.

"This issue of pensions channels all the discontentment," the leader of the hardline CGT union, Philippe Martinez, told Public Senat TV. "Today is going to be a very big day of mobilisation."

For Macron, what is at stake is his reformist credentials, both at home and with his European Union peers, as well as keeping public spending in check.

Pushing back the retirement age by two years and extending the pay-in period would yield an additional 17.7 billion euros ($A28 billion) in annual pension contributions, allowing the system to break even by 2027, according to labour ministry estimates.

Unions suggest other options such as taxing the super-rich or increasing employers' contributions or those of well-off pensioners.

Unions have described the day as a starting point, with more strikes and protests to follow.

The reform still needs to go through parliament, where Macron has lost his absolute majority but is hoping to get it adopted with the support of conservatives.

Public transport was severely disrupted on Thursday.

As few as one-fifth of high-speed TGV lines were operating, with barely any local or regional trains running, the SNCF rail operator said.

Seven out of 10 primary school teachers have said they would strike, their main union said.

French power supply was reduced at eight nuclear reactors and at some hydropower plants due to the strike, utility group EDF said.

Meanwhile, Macron and several of his ministers are in Barcelona on Thursday for a meeting with the Spanish government.