Also closed, therefore, was the Louvre's Leonardo Da Vinci exhibit marking the 500th anniversary of the Italian master's death, the museum said.

Several dozen protesters, including some Louvre employees, staged the demonstration after an appeal from several hard-left trade unions against President Emmanuel Macron's planned changes to the retirement system, which they said will "lower everyone's pensions."

Some protesters were singing "Mona Lisa in on strike, Leonardo is on strike."

It is the first time since the protest movement began on Dec. 5 that the Louvre and the Leonardo exhibit were fully closed. About 30,000 people visit the museum every day.

Some videos on social media showed angry visitors booing at protesters to express their disappointment.

Some of those shut out were upset, while a few of those interviewed expressed solidarity with the strikers.

"I think it's fine if they want to protest but they shouldn't block the plans of the people who have flown over here to see an exhibition of Leonardo," said Ben Garrett of Dallas, Texas.

Gerhard Jehle of Germany, who had bought his ticket in advance, shared that view, and said he was "badly informed about the extent of the strike."

"I don't understand how this happens," Jehle said. "Public transport doesn't function. The unions have to be controlled with an iron hand."

The weeks of strikes and protests have hobbled public transportation and disrupted schools, hospitals, courthouses and even opera houses and the Eiffel tower.

Argentinian Marcelo Campano, who also had a ticket, said that he understands workers' bid to confront a government they perceive as "neoliberal ... So we'll show our solidarity and come back another day."

Major French retailers Fnac Darty and Casino said that business in France was badly affected by the strikes, especially during the holiday season.

Fnac Darty said the strikes cost it around 70 million euros ($78 million) in lost revenue.

Casino cut its forecast for earnings growth in France, where it does more than half its business, to 5% in 2019, from a previous 10%. The company estimates that the strikes in December cost it about 80 million euros in lost revenue.

Shares in both companies were down by more than 5%.

The prime minister's office said earlier this week that the SNCF train authority and the RATP, which runs public transport, had lost over a billion euros since the start of the strike. Trains have suffered most, so far losing some 850 million euros.

While the number of striking workers has diminished since the movement, the country's trains and the Paris subway were still disrupted Friday.