Chris Froome has criticised Vincenzo Nibali after his rival pulled away to win stage 19 of the Tour de France while he fixed a problem with his bike.

Riders in the peloton have an unofficial agreement to avoid attacks while the leader is suffering with mechanical issues, but Froome was left helpless as he removed a stone from his brake callipers when Nibali stormed clear of the main group to claim victory.

"I told him exactly what I thought of him," the Team Sky rider told reporters. "I think it's pretty self-explanatory what happened.

"Nibali had the whole climb to attack, but he chose the moment I had a mechanical problem to make his move.

"Other riders have told me he turned to look over his shoulder, and he could see what was happening, but he carried on and it was very unsportsmanlike behaviour, not in the spirit of the Tour de France, and definitely not what this race is about."

Froome finished behind Nibali and Nairo Quintana on stage 19 but still leads the race by two minutes and 38 seconds ahead of Saturday's penultimate stage.