Valence, France: Slovakian Peter Sagan, of the Bora team, claimed his third win of the 105th Tour de France on Friday after sprinting to victory on the 13th stage.

Britain’s Geraint Thomas, fresh from winning two stages in the Alps, remained in the yellow jersey at the end of a 169.5km ride from Bourg d’Oisans to Valence that finished in a bunch sprint.

Welshman Thomas leads Sky teammate Chris Froome by 1min 39secs, with Dutchman Tom Dumoulin (Sunweb) third overall at 1:50.

Earlier in the day, Tour de France director Christian Prudhomme has demanded fans show more respect a day after Team Sky were booed off the podium and Vincenzo Nibali crashed out when his bike got tangled up.

He hinted there could be measures to stop fans running behind riders during the spectacular mountain stages that attract thousands to the roadside.

“They have only one wish, to be on television and take a selfie,” Prudhomme said.

“We have no wish to see that again.”

He added: “Rocket flares don’t belong on bike races. They make the riders breathe in noxious air, and they blind them.

“It just doesn’t make sense.”

Sky’s domination so far has seen Geraint Thomas win two key alpine stages in succession to lead the race by 1min 39sec from teammate and four-time champion Chris Froome. But their success is doing little to appease detractors.

Thomas was booed and jeered as he crossed the finish line on Thursday, then while he stood on the podium.

Earlier in the stage, a bag or camera strap got entangled with Nibali’s bike, sending the Italian, riding through a plume of smoke, crashing to the ground and on his way home after he suffered a fractured back.

Froome, who was reportedly spat at, also received a hearty slap on the back from an overzealous fan.

Although Tour chiefs have improved conditions for the peloton in recent years by limiting the sale of alcohol and having police motorbikes clear a path for the riders, Prudhomme said: “The climb up the Alpe d’Huez was painful.

“The riders of the Tour, the champions of this race, need to be respected.”

Sky have won five of the past six editions of the Tour, Bradley Wiggins beginning their impressive streak in 2012 and Froome winning in 2013 and then 2015-2017.