French President Emmanuel Macron faced nationwide protests on Labour Day on Monday as he struggles to turn the page on a deeply unpopular increase in the retirement age that has unleashed a wave of social unrest.

Macron's popularity has plunged to near record lows hit during the “Yellow Vest” crisis after he stared down trade unions and multi-sector strikes and lifted the retirement age by two years to 64.

The move crystallised anger against a president perceived by many as indifferent to their daily hardships and Macron has been met by boos, pot banging and heckles as he confronts citizens on walkabouts.

Unions hope more than 1 million people will march through towns and cities on Monday.

"This May 1st will be a milestone,” said Sophie Binet, leader of the hardleft CGT union.“It will serve to say that we will not move on until this (pension) reform is withdrawn.” Laurent Berger, head of the reform-minded CFDT trade union, said Macron's government was deaf to the demands of one of the most powerful social movements in decades.

Even so, he said on Sunday that did not mean an end to talks with the government. Macron says the reform is needed to keep one of the industrialised world's most generous pension systems in the black.

French pension payments as a share of pre-retirement earnings are comfortably higher than elsewhere and a French man typically spends longer in retirement than those in other OECD nations.

But the trade unions say the money can be found elsewhere. Macron's government, which lacks a working majority in parliament, rammed the pension legislation through without a final vote due to a lack of cross-party support.

A hardening of the political opposition risks complicating the rest of his reform agenda, including an employment bill that would require those receiving the minimum welfare benefit to work or get training for 15-20 hours per week.

Fitch cut France's sovereign credit rating on Friday by one notch to 'AA-', saying a potential political deadlock and social unrest posed risks to Macron's agenda.