Rohan Dennis abandoned the Tour de France in bizarre circumstances as his Bahrain Merida team “launched an investigation” into his whereabouts, only for the rider to turn up at his team bus minutes later.

Time-trial world champion Dennis, one of the favourites for Friday’s individual effort against the clock, pulled out 80km from the finish of Thursday’s 12th stage, organisers said.

According to French TV, Dennis was seen arguing with his team car before climbing off his bike. No official explanation has yet been given for his withdrawal from the Tour.

“Our priority is the welfare of all our riders so will launch an immediate investigation but will not be commenting further until we have established what has happened to Rohan Denis,” Bahrain Merida said in an alarming statement.

But Norwegian broadcaster TV2 soon reported that Dennis was in his team bus, with his bike pictured outside, and he was later seen walking from the bus to the finish line.