Thousands of people took to the streets across France on Saturday to protest against President Emmanuel Macron's decision to appoint centre-right Michel Barnier as prime minister, with left-wing parties accusing him of stealing legislative elections.

Macron named 73-year-old Barnier, a conservative and the European Union's former Brexit negotiator, as prime minister on Thursday, capping a two-month-long search following his ill-fated decision to call a legislative election that delivered a hung parliament divided in three blocs.

In his first interview as government chief, Barnier said on Friday night that his government, which lacks a clear majority, will include conservatives, members of Macron's camp and he hoped some from the left.

Barnier faces the daunting task of trying to drive reforms and the 2025 budget, as France is under pressure from the European Commission and bond markets to reduce its deficit.

The left, led by the far-left France Unbowed (LFI) party, has accused Macron of a denial of democracy and stealing the election after Macron refused to pick the candidate of the New Popular Front (NFP) alliance that came top in the July vote.

Pollster Elabe published a survey on Friday showing that 74 percent of French people considered Macron had disregarded the results of the elections with 55 percent believing he had stolen them.

In response to the appointment of Barnier, whose centre-right Les Republicains party is only the fifth bloc in parliament with less than 50 lawmakers, left-wing party leaders, unions and student bodies called for mass protests on Saturday ahead of new action, including possible strikes on October 1.

The LFI party said 130 protests would take place across the country. (Reuters)