Macron had hoped the elections would help anchor his young party in towns and cities across France, including Paris, before an anticipated 2022 re-election bid.

But aides had more recently been playing down expectations and the sweeping wins by the Greens, who in some cities joined forces with leftist allies, may compel Macron to reshuffle his government to win back disenfranchised left-wing voters.

In a rare bright spot for Macron, his prime minister, Edouard Philippe, won his bid to become mayor of the northern port city of Le Havre.

Exit polls showed the Greens winning in Lyon, Marseille, Bordeaux and Strasbourg, building on the momentum created by their strong performance in France in last year's European Parliament elections.

In Paris, the biggest prize of all, the incumbent Socialist mayor Anne Hidalgo celebrated victory after a shambolic campaign by Macron's camp.

In Perpignan, Marine Le Pen's far-right Rassemblement National claimed victory, the first time it has taken control of a town of more than 100,000 people.

France's 35,000 mayors set policy on issues from urban planning to education and the environment.

In this second round of voting, turnout was only about 40 per cent and people wore masks because of the novel coronavirus pandemic.

The weak performance of Macron's La Republique en Marche will prompt much soul-searching for the president.

Early in his term, left-wing opponents derided Macron as a "president of the rich" while he eased taxes on companies and relaxed worker protections as he enacted reforms to liberalise France's economy.

The reforms were bearing fruit: growth was robust among euro zone peers and stubbornly high unemployment was falling.

But the past three years have been mired in social unrest and the pandemic's is reversing some of Macron's hard-fought gains.

Australian Associated Press