Basketball star Victor Wembanyama joined other leading French athletes on Thursday in warning against voting for the "extremes" in this weekend's parliamentary election.

Polls show the anti-immigration National Rally (RN) party could emerge as the biggest parliamentary group and head a government for the first time in what would be a seismic change for France.

"Of course, political choices are personal, but for me it is important to take a distance from extremes, which are not the direction to take for a country like ours," the San Antonio Spurs phenomenon, who is expected to represent France at the Paris Olympics, told reporters in Paris.