against French President Emmanuel Macron's plan to reform the pension
system gathered momentum on Tuesday, with more than 1.27 million
people in the street according to the interior ministry.
The number of demonstrators increased slightly compared to a first round of protests on January 19, putting pressure on the government which is struggling to convince voters of the need for the changes.
"The government must hear the massive rejection of this project and withdraw it," Patricia Drevon from the Force Ouvriere union told a joint press conference with other labour leaders on Tuesday evening.
Two more days of strikes and protests were announced for next week on Tuesday and Saturday.
Macron's plan to raise the age of retirement from 62 to 64 is a flagship policy of his second term in office which he defended on Monday as "essential" given forecasts for deficits in the coming years.
"The reform of the pension system is causing questioning and doubts. We hear it," Prime Minister Elisabeth Borne wrote on Twitter on Tuesday, while insisting on the government's "responsibility" to carry out the changes.
Unions claimed turnout nation-wide on Tuesday was around 2.5 million, with the hard-left CGT suggesting 2.8 million earlier in the day.
Strikes crippled transport, schools and other public services around the country.
"It's one of the biggest demonstrations organised in our country in decades," the head of the moderate CFDT union, Laurent Berger, said as a large crowd dominated by union members, public sector workers and students began marching in Paris.
The last comparable protests were in 2010 -- also against pension reform -- which reached 1.23 million people at their peak according to official figures, and 3.5 million according to unions.
Despite the prospect of an increasingly bitter and costly stand-off, Macron has shown no sign of stepping back over an issue that has put his credibility on the line only nine months after his re-election.
France currently has the lowest qualifying age for a state pension among major European economies and spends the second-highest amount on pensions relative to the size of its economy compared to other industrialised countries, according to OECD data.
"We need people to join the movement, rolling strikes that have a real impact," Viviane Rongione, a retired teacher, told AFP as she marched on Tuesday. "Protests every 10 days won't be enough to make the government back down."
Tuesday's demonstrations were peaceful, but minor scuffles broke out in Paris in the afternoon between anarchist and far-left activists and police. Police said they had arrested 18 people.