France's Constitutional Council on Friday prepared to hand down its verdict on President Emmanuel Macron's unpopular pension reform, which could clear the way for the changes to be implemented.

Barriers have been erected in the streets near the court in central Paris and anti-riot police have been deployed to guard its headquarters, with potentially violent protests feared later when the decision is announced at 6:00 p.m. (1600 GMT).

The country has been rocked by three months of demonstrations and strikes over Macron's bid to raise the retirement age to 64 from 62, with around two in three voters against the changes, according to polls.

Experts believe the most likely scenario on Friday is that the nine-member Constitutional Council will censure some non-essential parts of the legislation but approve the main elements.

"The council will likely follow the course it always had -- not to counter big social or societal reforms," constitutional expert Laureline Fontaine told AFP.

But labor unions and opposition lawmakers are still hoping for a decision to strike down the changes that Macron championed during his first period in office and put at the heart of his second term which began last May.

A rejection of the law "would be a disaster for Emmanuel Macron," political journalist Ludovic Vigogne, who has written a recent book on the president, told RTL radio on Friday.

"He would have no margin for maneuver... it would be such a huge victory for his political opponents."

Police are expecting up to 10,000 protesters in the capital later Friday, including hundreds of radical leftists, a source told AFP.

Several possible demonstrations are being monitored at the city town hall and at the Louvre museum, not far from the Constitutional Council.

(Cover: Musicians perform during a concert by an "inter-orchestra/entertainment workers" symphonic orchestra to protest a pensions reform, as the Council of State is reflected in mirrors, on the Place du Palais Royal in Paris, France, April 9, 2023. /CFP)