French demonstrators on Thursday kicked off another day of protests and strikes to denounce President Emmanuel Macron's pension reform, after the latest talks between the government and unions ended in deadlock.

Macron, currently on a visit to China, is facing the biggest challenge of his second term over his flagship pension overhaul, which includes hiking the retirement age from 62 to 64 and demanding people work longer for a full pension.

Demonstrations got under way across the country, with striking workers waving labour union flags at the Charles de Gaulle Airport near the capital, television footage showed.

Protesters in the western town of Vannes started the day dancing a conga and listening to music from a brass band, while crowds also gathered in the western city of Nantes and southern port of Marseille.

There have been signs that the two-and-a-half-month protest movement is starting to lose some momentum, and unions are hoping for a mass turnout on the 11th day of action since January.

All sides in the standoff are awaiting an April 14 verdict on the validity of the reform by France's Constitutional Council, which has the power to strike out some or even all of the legislation.

While the members of the Constitutional Council -- known as the "wise ones" (les sages) -- will deliver their verdict in line with a strict interpretation of the law, unions want to show that the protest movement still has momentum whatever the decision.

"We're still asking for the reform to be revoked," Laurent Berger, head of the centrist CFDT union, told RTL radio on Thursday morning.

"We're in the middle of a social crisis, a democratic crisis," he said.

"It's a problem... that needs to be solved by the president."

Protests descended into violent unrest after Prime Minister Elisabeth Borne invoked on March 16 a controversial executive power to ram the bill through parliament without a vote.

Police are expecting 600,000 to 800,000 people to protest nationwide on Thursday.

- 'Democratic crisis' -

Unions said a meeting with Borne on Wednesday made no progress after she refused to discuss going back on the minimum retirement age of 64.

"It's clearly a failure when the prime minister won't even allow a way into that discussion," said Cyril Chabanier, speaking for the country's eight main unions after barely an hour of talks.

It was the first such gathering between the two sides since the government presented the contentious pensions bill in January.

Despite refusing to budge on the issue, Borne said she would not move forward with any other labour topics "without social partners".

Berger already on Wednesday said France was experiencing "a grave democratic crisis".

Macron is to remain for the rest of the week in China, where an aide denied the allegation as the pension change was in the president's manifesto during his re-election campaign last year.

"You can't speak of a democratic crisis when the bill has been enacted, explained to the public and the government is taking responsibility for it," said the aide, asking not to be identified by name.

Union chiefs have urged a record protest turnout on Thursday.

But numbers in the previous round of strikes and protests last Tuesday were down on the week earlier.

A record number of people, more than 1.2 million, marched against the reform nationwide on March 7.

The Paris metro system is for the first time on a strike day expected to be working with minimal disruption, according to operator RATP.

Across the country, three high-speed trains out of four will be running, railway operator SNCF said.

Just 20 percent of schoolteachers are expected to strike on Thursday, the Snuipp-FSU union said.

- 'Intermediate moment' -

Political analyst Dominique Andolfatto said Thursday's action would be an "intermediate moment" before the Constitutional Council gives its verdict on April 14.

"Not everything depends on today, but the unions cannot mess up this day either," he told France Info.

"If there is a lower turnout, the government will think its patience has paid off".

The government has argued that the changes are necessary to prevent the pensions system from plunging into deficit.

In the rest of Europe, people mostly retire in their late sixties as life expectancy has increased.

Critics say the pensions reform is unfair for people in tough jobs who start working early, as well as women who interrupt their careers to raise children.

If the Constitutional Council gives its green light, Macron will be able to sign the changes into law.

But the standoff has eroded his popularity, with a poll suggesting Wednesday that far-right leader Marine Le Pen would beat him if the presidential election of last year were repeated now.

The survey from the Elabe group for BFM television indicated Le Pen would score 55 percent and Macron 45 percent if they faced each other in a run-off vote.