Nine people were arrested and scores fined in Marseille as thousands took part in carnival celebrations despite COVID-19 restrictions.
Authorities say about 6,500 people took part in the carnival procession in the French city on Sunday.
Images posted on social media showed crowds tightly packed together and many people not wearing masks.
A spokeswoman for the Ministry of Interior told FranceInfo radio on Monday that "there have been several dozens of fines, nine arrests" so far.
"It is completely unacceptable while all the French make efforts, adapt, organise themselves to respect the various regulations that take place to fight against this epidemic, we see a number of revellers who have, in total irresponsibility, participated in this carnival," she added.
Marseille Mayor, Benoit Payan, said on Twitter that he is "angry".
"The selfish behaviour of a few irresponsible people is unacceptable. They will have to answer for their actions before the courts," he also said.
One of his deputies, Michèle Rubirola, in charge of health, has urged people who took part in the parade to get tested as quickly as possible, stressing that they are "not enough intensive care beds and vaccines".
France has recorded more than 30,000 new confirmed infections for five consecutive days and has the EU's second-highest COVID-19 death toll — 92,305 — after Italy.
Prime Minister Jean Castex said last week that this "third wave" can be attributed to the spread of the British variant which now accounts for about three-quarters of all new cases.
Castex said that the variant is not only "more contagious" but also "more virulent and potentially more serious."
Sixteen of the country's 96 départements entered another lockdown over the weekend until at least mid-April. These include Paris and its wider region as well as the Alpes-Maritimes, where the cities of Nice and Cannes are located.