Protestors blocked the road and let off pink flares, forcing all riders to stop around 36 kilometres from the finish in Megève.

Armed police forcibly moved the activists including one wearing a T-shirt with the message "We have 989 days left", before the race resumed following a 10-minute delay.

An environmental activist group, called Derniere Renovation, said it was behind the protest.

"Since the Government doesn't care about the climate crisis, we need to come and take over the Tour de France to refocus attention on what matters for our survival," a statement from the Derniere Renovation read.

"We need to make our Government react as they lead us to the slaughterhouse."

Following the delay, the race ended with a photo finish as Cort Nielsen pipped Australian Nick Schultz on the line.

Cort Nielsen of EF Education-EasyPost finished the 148.5km stage from Morzine to Megève in 3 hrs 18 mins 50 secs.

Schultz of BikeExchange-Jayco had to settle for second place as Spain’s Luis Leon Sánchez of Bahrain Victorious and American Matteo Jorgenson of Movistar Team came third and fourth respectively.

"It’s unbelievable," Cort Nielsen said.

"I can’t believe what just happened.

"I was on the limit for so long on this climb but luckily I had Bettiol who was really strong in the front and that meant I could sit on and save some energy.

"I was losing the group a couple of times in the last kilometres but suddenly it all came back together and I was able to take it in the sprint.

"It’s huge.

"For my type of rider it can’t be any bigger than this."

Two-time winner and defending champion Tadej Pogačar of Slovenia remains in the yellow jersey, although his lead has been cut to 11 seconds by Germany’s Lennard Kämna of Bora–Hansgrohe.

Pogačar’s chances of claiming a third successive title have also been hit by further COVID-19 cases in the UAE Team Emirates team.

New Zealander George Bennett has joined Norway’s Vegard Stake Laengen in being forced to pull out of the competition after testing positive for the virus.

Poland’s Rafał Majka has also contracted COVID-19 but will remain in the team.

Competition is due to continue tomorrow with the 157km mountain stage from Albertville to Col du Granon.