More than 1.2 million protesters marched in France on Tuesday as rail workers and refinery staff began rolling strikes and trade unions stepped up their campaign to try to stop Emmanuel Macron’s plan to raise the pension age to 64.

For the sixth time since the start of the year, trade unions called a nationwide day of strikes and demonstrations. Many protest rallies attracted bigger crowds than previous ones organised since mid-January, including in Marseille, one of France’s biggest cities, authorities and local media said.

“The idea is to bring France to a standstill,” said Fabrice Michaud of the railway workers’ branch of the CGT trade union.

Rail unions called for rolling, open-ended strikes, which could affect all national trains as well as international routes including the Eurostar. Bin collectors and truck drivers joined the action.

By midday, approximately 39% of workers at the state rail operator SNCF were on strike, a union source told Agence France-Presse – the highest number since the first strike against the pension changes on 19 January.

Local urban buses and subway trains in large cities were affected, as were airlines, with up to 30% of flights cancelled on Tuesday and Wednesday as air traffic controllers went on strike. About 24% of public sector workers stopped work, and many schools closed as teachers held a one-day strike. Some students, including at Rennes 2 University in Brittany, began blockading faculties on Monday night.

Refinery and energy workers also took part in strikes. The CGT union said fuel deliveries from refineries across France had been blocked from Tuesday morning, which could see petrol stations running short if the protests continue.

“The government has to take this [resistance] into account when there are so many people in the street, when the government is having so much trouble explaining and passing their reform,” Laurent Berger, the head of the moderate CFDT union, said at a Paris demonstration.

Macron’s proposals to raise the retirement age from 62 to 64 and increase the number of years of work required to claim a full pension are being debated in the French senate.

Macron has been left severely undermined on the domestic front after his centrist grouping failed to win an absolute majority in parliamentary elections last June amid gains for the far right and radical left.

Without a majority, the government must rely on the rightwing Les Républicains to back pensions changes, but their senators and lawmakers are pressing for alterations.

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Discussions are forecast to conclude by the end of March. It is expected that a committee made up of legislators from both houses of parliament will seek a potential deal on a joint version of the text, to eventually be presented for approval at the national assembly and then the senate. But tensions remain as to the level of support.

The government is determined to press on with the pensions changes, and its spokesperson said there were more important issues facing the country than the strikes, such as the cost of living crisis.

“I can understand that not many people want to work two more years, but it’s necessary to ensure the viability of the system,” the prime minister, Élisabeth Borne, told France 5 TV.

An Ifop poll for the Sunday paper Le Journal du Dimanche found that only 32% of French people supported Macron’s pension changes. An Elabe poll found 56% of French people supported rolling strikes, and 59% backed the call to bring the country to a standstill.

Read more @TheGuardian