Two-time Tour de France champion Jonas Vingegaard broke his collarbone and several ribs after a horror mass crash during stage four of the Tour of the Basque Country on Thursday.

"It was a terrible fall but thankfully he is in a stable condition and conscious," his team Visma-Lease a Bike reported on X.

"Tests in hospital have revealed that he has suffered a broken collarbone and several ribs. He remains under supervision at the hospital," the team added on the social media platform.

Belgian ace Remco Evenepoel was another to emerge battered and bruised from the horror accident.

"Remco will return to Belgium tomorrow to be operated on a broken collarbone and pass further tests at the hospital at Herentals," his Soudal-Quick Step team announced.

His injuries have ruled him out of upcoming one-day classics in the Netherlands and Belgium.

Other big names involved in the crash who were taken to hospital were Jay Vine and Steff Cras, while Primoz Roglic was also involved and did not finish the stage.

"Over the radio we heard that Jonas was involved in a big crash," said Visma sports director Addy Engels. "We immediately saw that it didn't look good when we arrived to him."

Despite the gravity of Vingegaard's injuries they came as almost a sense of relief that they were not more serious.

Several of the 12 riders involved in the crash fell into a concrete ditch after sliding off on a corner with around 35 kilometres to go in the run from Etxarri Aranatz to Legutio, in northern Spain. (AFP)