The French government warned restaurant owners Monday that illegal openings would jeopardise their COVID-19 aid, as several defied the pandemic shutdown to serve meals in protest of a measure they say is increasingly untenable.

Cafes and restaurants were ordered to close since October 30 to curb the pandemic, and cash-strapped owners fear it will be several months before they can get back to business as usual.

"All I'm asking for is the right to work," said Stephane Turillon, a chef in Cusance, eastern France, who launched his campaign for a nationwide protest last month.

Around 100 people gathered in tents he set up outside "La Source Bleue", but after discussions with police and his lawyer he refrained from serving a sit-down meal, offering dishes as takeaway instead.

"We're not going to reopen because I risk having to go to jail or losing my financial aid," Turillon told journalists.

He later led a protest march of some 250 people to the local cemetery to place his apron and a French flag to honour "French artisans" forced to close during the pandemic.

Dozens of owners emulated his call to action, saying they could not survive on takeout service or deliveries alone, even with the government offering thousands of euros a month to businesses forced to close during the health crisis.

Kathia Boucher offered a single item, a hearty potato-and-cheese gratin known as tartiflette, at her brasserie in Ligescourt, northern France, where clients were spaced two metres apart.

"My sales from today will go toward paying my fixed costs," said Boucher, who said she had gotten work at a car part factory as well as cleaning jobs in order to make ends meet.

The protests came as Paris police said Saturday that agents had discovered 24 restaurants operating illicitly last Thursday and Friday alone, and warned they would step up checks following reports of dozens of similar cases in recent weeks.