Team Sky's Jonathan Castroviejo is out of the Tour of the Basque country with multiple fractures but Geraint Thomas, involved in the same mass pile-up, is clear to race on, the team said Thursday.

Both riders were involved in Wednesday's crash that decimated the peloton on the third stage of the tour.

Another victim, Frenchman Julian Alaphilippe, among the race favorites, was forced to pull out of Thursday's fourth stage as a result of injuries sustained in the crash, his team, Deceuninck-Quick Step, said.

Tour de France winner Thomas was able to remount and finish Wednesday's stage but Castroviejo was taken to hospital and underwent tests.

"Jonathan has a fracture of his right clavicle, as suspected," team doctor Inigo Sarriegui said.

"One of his ribs is fractured, he has a very small fracture on his left wrist, and he has a stable fracture of parts of his vertebrae."