Trade union protesters angered by President Emmanuel Macron's move to raise the French retirement age without a final vote in parliament blocked the Louvre museum in Paris on Monday, frustrating crowds of visitors.

Demonstrating peacefully against plans to make most French work an extra two years to 64 to balance the pension budget, a small number of protesters gathered at the foot of the Louvre's glass pyramid. One banner read "Retire at 60 - work less to live longer."

A queue of disappointed tourists snaked through the courtyard.

"This is ridiculous, we come from everywhere in the world with our children to visit a museum and it’s ridiculous that 20 people are blocking the entrance," said Samuel, a Mexican tourist who did not give his surname.

"I really understand where they're coming from, and it's fair enough. But we all would like to go and see 'Mona Lisa', but never mind," said Jane, a visitor from London.

Louvre employees were among the protesters outside the famed musemum. A Louvre tour guide came out to address the visitors. "We hope you understand our reasons," she said.

The protest came one day ahead of a 10th round of nationwide strikes and street marches and followed violence in cities across France over the pension system changes.

Separately, Paris police said they were carrying out an operation to prevent unauthorised gatherings in front of the Centre Pomopidou, another landmark museum in Paris.