Tour de France director urges fans to respect cyclists and curb unruly behaviour

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 ahead of the 13th stage from Bourg d'Oisans to Valence.

"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."

Team 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 was reportedly spat at during the stage.

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."