France's trade unions headed for a crucial face-off against President Emmanuel Macron on Tuesday, with fresh strikes and protests planned against a controversial pensions reform that would push back the retirement age for millions.

Unions have vowed to bring the country to a standstill over the proposed changes, which include raising the minimum retirement age to 64 from 62 and increasing the number of years people have to make contributions for a full pension.

"I call on all the country's employees, citizens and retirees who are against the pensions reform to come out and protest en masse," the head of the CFDT union Laurent Berger told the France Inter radio station Monday.

"The president cannot remain deaf" to the protests, he added.

Macron put the plan at the center of his re-election campaign last year, and his cabinet says the changes are essential to prevent the pensions system from falling into deficit in the coming years.

But they face fierce resistance from both parliament and the street, with almost two in three people across the country supporting protests against it, according to a poll by the Elabe survey group published Monday.

Unions have warned of rolling strikes on public transport that could paralyze parts of the country for weeks on end.

Police expect 1.1 million to 1.4 million people to hit the streets Tuesday in more than 260 locations nationwide, a source has told AFP on condition of anonymity.

Only one in five regional and high-speed trains are expected to run, while a leading trade unionist representing refinery workers has vowed to bring the French economy "to its knees."

(Cover: A demonstration on the fifth day of nationwide rallies organized since the start of the year, against a deeply unpopular pensions overhaul, in Nantes, western France, February 16, 2023. /CFP)