After being booed off the podium on Thursday and with teammate Chris Froome spat at on Stage 13, Tour de France leader Geraint Thomas hit back at the doubters on Friday by claiming Team Sky are racing “100 per cent” clean.

Thomas, the former Olympic champion in track cycling, was dramatically booed off the podium after claiming his second successive stage win in the high Alps to reinforce his overall lead on Thursday.

It was a lead he retained on Friday as the race returned to a sprint finish, with Slovakia’s Peter Sagan edging UAE Team Emirates’ rider Alexander Kristoff to claim victory – his third stage win of the 2018 Tour.

It was a bittersweet day for Welshman Thomas and Team Sky who saw their team leader and four-time champion Chris Froome spat at and pushed heavily by one of the many over-enthusiastic fans who line the 13.8km route to the summit.

Team Sky’s dominance of the race has caused the doubters to compare their performances to those of US Postal, the team once led by drugs cheat Lance Armstrong.

Armstrong, who won the Tour a record seven times, saw all his cycling results erased when he finally admitted he had taken performance-enhancing drugs throughout his career.

But Thomas, who has a real chance of upstaging Froome to win the yellow jersey if the Kenya-born champion fails to step up in the crucial third week, said the doubters are wrong.

“I 100 per cent believe in myself and the team, that we do everything in the right way, along with the majority of the peloton as well,” said Thomas.

“I can’t say 100 per cent for the peloton, but 99 per cent I’m sure that everyone’s doing it the right way, working hard.

“I think it’s great for the sport. You look at all the anti-doping and all the tests and that type of stuff, and then you look at other sports.

“Cycling’s leading the way by a million miles, so I have every confidence in the sport at the moment.”

At the end of the mainly flat 13th stage, Thomas looked sheepish as he stepped on to the podium to be presented with the yellow jersey.

In comparison to Thursday, there were practically no boos or whistling, incidents that were condemned earlier by race director Christian Prudhomme.

“All I can do is renew calls for calm, for good sense and for serenity with regard to the riders on the Tour de France,” Prudhomme said.

“Don’t whistle and, obviously, don’t touch the riders. Even if it’s just an over-friendly backslap.”

Thomas, who takes a 1min 39sec lead over Froome into Saturday’s undulating stage to Mende, said he is prepared for the flak.

“Obviously, you’d prefer everyone to cheer you, but I can’t affect that,” he said.

“I’d rather be on the podium getting booed than sat on the bus and being cheered.”