FRENCH Prime Minister Elisabeth Borne has insisted that government plans to raise the retirement age from 62 to 64 are “no longer negotiable,” even as unions prepare for a mass walkout this week.

Her remarks in a radio interview on Sunday further angered trade unions and the parliamentary opposition.

Unions plan to hold new mass protests and strikes on Tuesday over the attack on pensions.

Raising the pension age is part of a wide-ranging Bill that constitutes the flagship measure of President Emmanuel Macron’s second term.

Speaking on France Info on Sunday, Ms Borne said that the measure was not open to further negotiation.

Retirement at 64 and a lengthening of the number of years needed to earn a full pension “is the compromise that we proposed after having heard employers’ organisations and unions,” she added.

While unions have welcomed the government’s readiness to negotiate on other parts of the plan, they say that the proposed 64-year-old threshold has to go.

In a rare show of unity, France’s eight major trade union centres have all branded the government’s scheme “unfair” and plan to “mobilise even more massively” for Tuesday’s actions than the two-million-strong show of opposition at rallies on January 19.

“It’s looking like there will be even more people,” said Celine Verzeletti, a leading member of the left-wing General Confederation of Labour (CGT).

Pointing to opinion polls, Laurent Berger, head of the centrist CFDT union centre, said that “the people disagree strongly with the project, and that view is gaining ground.”

It would be “a mistake” for the government to ignore the mobilisation, he warned.

Communist Party general secretary Fabien Roussel labelled Ms Borne’s remark “a provocation,” saying that the prime minister was “blinkered” and her government “inflexible.”

Some 200 protests are set to take place across France on Tuesday, with a big march planned for Paris followed by a rally outside the National Assembly, where parliamentary commissions began examining the draft law today.

Legislator Manuel Bompard, whose left-wing France Unbowed party opposes the reform, called for “the biggest possible” turnout for the strikes and protests.

“We have to be in the streets on Tuesday,” he told BFM television on Sunday.

The government claims that raising the pension age is necessary to keep the pension system solvent as life expectancy in France has grown and birth rates have declined.

According to a new poll, over two-thirds of French people (68 per cent) are against the measure.