By Antony Paone, Sarah Meyssonnier and Ingrid Melander

PARIS (Reuters) -Clashes erupted in Paris next to a Left Bank brasserie favoured by French President Emmanuel Macron as protesters torched garbage cans and smashed two banks during the eleventh day of nationwide demonstrations against pension reform.

The bistro La Rotonde, whose awning was set alight as protesters threw bottles and paint at police, is known in France for hosting a much-criticised celebratory dinner for Macron when he led the first round of the 2017 presidential election.

Protests against the flagship reform of Macron’s second term, which lifts the retirement age by two years to 64, began in mid-January and have coalesced widespread anger against the president.

Labour unions on Thursday evening called for another day of nationwide protests on April 13.

“Strike, blockade, Macron walk away!” protesters chanted in the western city of Rennes, where police fired tear gas at protesters who threw projectiles at them and set bins on fire.

The street protests have become increasingly violent since the government pushed the pension legislation through parliament without a final vote due to a lack of support among lawmakers.

But police estimates indicate the number of people taking part may be falling.

On Thursday, black-clad anarchists smashed the windows of two banks and engaged riot police in cat-and-mouse skirmishes along the route of the street protest.

One police officer briefly lost consciousness after being struck on the helmet by a rock.

A total of 77 police force members were injured and 31 people were arrested as of 1820 GMT in Paris, police said.

Polls show a wide majority of voters oppose the pension legislation. But a source close to Macron said that was not what mattered.

“If the role of a president of the republic is to make decisions according to public opinion, there is no need to have elections,” the source said. “Being president is to assume choices that may be unpopular at a given time.”

‘WITHDRAW THE REFORM’

Union leaders and protesters said the only way out of the crisis was for the legislation to be scrapped, an option which the government has repeatedly rejected.

“There is no other solution than withdrawing the reform,” the new leader of the hardline CGT union, Sophie Binet, said at the start of the Paris rally.

The number of people striking in schools and disruption to train traffic was down on Thursday from a week earlier. On the streets, the hardline CGT said about 400,000 people joined the protest in Paris, down from 450,000 the week before. The interior ministry said 57,000 people attended in Paris, down sharply from the 93,000 reported a week earlier.

Nationwide, 570,000 people marched against the reform on Thursday, down from 740,000 a week earlier.

The numbers could bring some hope to officials who say they believe the rallies may be losing steam.

Laurent Berger, the leader of the moderate CFDT union told France 5 television that the figures were hefty for an eleventh day of protests.

“The real issue is that there is widespread resentment and social anger,” Berger said, adding he condemned the violence.

A crucial date on the issue looms on April 14, when the Constitutional Council delivers its verdict on the pension bill. Constitutional experts say the council is unlikely to strike the legislation down, which may help weaken protests.

“Mobilisation will continue, one way or another … It’s a long distance race,” the CGT’s Binet said.

At the Paris rally, nurse Soraya Bouadouia said: “I will be here until the withdrawal of the pension reform, which is a completely unacceptable reform.”

With Macron on an official trip to Beijing, one protester held a banner that read: “Macron resign. You will hear us all the way to China.”

(Additional reporting by Stephane Mahe, Silvia Aloisi, Tassilo Hummel, Lucien Libert, Noemie Olive, Elizabeth Pineau, Michel Rose, Benoit Van Overstraeten; Alain Acco, Dominique Vidalon ; writing by Ingrid Melander; editing by Hugh Lawson, Mark Heinrich, Nick Macfie and Deepa Babington)

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