French police are searching for two thieves who stole 25,000 euros in coins and bullion from a gold store during a protest against pension reforms, a local prosecutor announced.

On Saturday, French President Emmanuel Macron signed his unpopular reform law to raise the retirement age from 62 to 64, fueling anger across the country.

As protests broke out in Rennes, in western France, later that day, the manager of a gold shop who was downstairs at the time heard a commotion upstairs, according to city prosecutor Philippe Astruc.

"As the protesters were walking outside, I noticed that three of the shop's windows were broken," said Astruc.

He added that when she opened the door to inspect the damage, "two people stormed the store, and the first snatched coins and gold bars, while the second quickly grabbed her by her forearms."

The thieves left the place after looting valuables worth about 25,000 euros ($27,000).

Agence France-Presse correspondents said that more than a thousand people participated in the protests that took place on Saturday in the city of Rennes, which included skirmishes between demonstrators and the police.

The night before, after the country's constitutional court approved the reform after three months of largely peaceful protests against it, several storefronts in the city were damaged.

The socialist mayor of Rennes, Nathalie Abery, told AFP the city center had been "looted" in the clashes.