PARIS — French Prime Minister Edouard Philippe warned on Tuesday of a lengthy battle over the government's pension reforms, as hundreds of thousands of people demonstrated on the sixth day of a transport strike that has caused travel misery.

The industrial action, which has paralyzed public transport in Paris and severely disrupted national rail services, is the biggest show of union force since President Emmanuel Macron came to power in 2017 vowing to cut public spending and make the economy more competitive.

On Tuesday, 339,000 people took part in a second day of demonstrations over the government's plans to merge the country's 42 separate pension schemes into one, according to interior ministry estimates.

While significant, the numbers, which unions claimed were far greater, were markedly down on the first day of the strike on Dec. 5, when more than 800,000 people took to the streets.

The protests aim to keep up pressure on the government, a day before Philippe sets out the eagerly-awaited details of the pensions overhaul.

On Tuesday, the premier downplayed the prospect of a speedy breakthrough in the dispute, saying there would be "no magic announcements" that would bring the protests to a sudden halt.

"It's not because I'm giving a speech that the demonstrations will stop. The speech will even raise new questions, and that's how it should be," he told MPs from Macron's centrist Republic on the Move (LREM) party.

Those opposing the reform accuse former investment banker Macron of trying to roll back France's costly but highly cherished welfare state.

The official retirement age in France is 62, one of the lowest among developed countries.

The government has argued that getting the French to work longer is necessary to keeping the system afloat.

On Tuesday, Philippe tried to reassure the train drivers, electricity workers, ballet dancers and other workers who retire earlier or with more generous pensions than the average private sector employee, that the changes would be gradual.

"We will not call into question those who are benefiting from them (special retirement schemes)," he said, hinting that the changes will only affect younger generations.

France's famously militant unions have so far sounded an uncompromising note, however, insisting that they will not call off the strike unless the reform is scrapped outright.

The strike has revived memories of three-week-long strikes over pension reforms that crippled France in 1995, forcing the center-right government of the day to reverse course.

Teachers joined the industrial action on Tuesday for the second time in a week, but with only 12 percent of primary teachers and 19 percent of secondary teachers walking out far fewer schools were closed than on Dec. 5.

Julien Sergere, a 38-year-old teacher who marched in Paris, said he was worried that a proposal to bring the way pensions are calculated in the public sector in line with those in the private sector would leave teachers poorer.

"Our wages are low and until now the advantage we had was that our pensions were calculated on the basis of the last six months of our career, which compensated a bit.

"But today, they're talking about (basing calculations on) the last 25 years, which could make our pensions fall by between 500 and 900 euros ($550-1,100) a month on average," he said.

Disgruntled hospital workers, firefighters, students and "yellow vest" anti-government protesters also took part in Tuesday's rallies, reflecting the broad level of dissatisfaction with Macron's policies half-way through his mandate.

"Make our pensions great again!," read a placard held aloft by a demonstrator in Paris, reprising the president's 2017 pledge to "Make our planet great again.

Striking workers blocked seven petrol refineries but the government said there had been no impact on petrol supplies.

Meanwhile, public transport in the capital remained at a near standstill, with only two of 16 metro lines running as normal, nine completely closed and suburban trains also heavily disrupted.

The head of commuter trains at state railway company SNCF, Alain Krakovitch, warned on Tuesday that he expected the chaos to continue "until the end of the week" but some labor leaders have vowed to fight through until Christmas.

"Pensions are the glue of all discontent," the leader of the hardline CGT union Philippe Martinez told France 2 television. — AFP