Britain's Mark Cavendish left, sprints prior to crash during the sprint of the fourth stage of the Tour de France. Photo: Christophe Ena/AP

German sprinter Andre Greipel hit out at Peter Sagan after the world champion elbowed Mark Cavendish into the safety barriers in the sprint finish to Tuesday's Tour de France fourth stage.

A bleeding Cavendish was taken to hospital by ambulance with his arm in a sling and nursing finger and shoulder injuries after crashing hard 100 metres from the finish line.

Sagan, who was kicked out of the Tour for his action, had shoved an elbow into Cavendish in the sprint finish to the 207.5km stage from Mondorf-les-Bains to Vittel, causing a spectacular crash.

And Greipel's manager at Lotto-Soudal Marc Sergeant said the German was fuming at Sagan for his sprint tactics.

"I asked Andre. He was quite pissed (off) by the attitude of Sagan, making some moves which he shouldn't make," Sergeant told Eurosport. 

"Yesterday it was the same thing in the intermediate sprint, he gave an elbow to Andre and he (Greipel) was a little bit pissed (off) yesterday already.

"Twice in a row is too much. Greipel was saying, 'He isn't my friend anymore from now on'."

At the finish, Sagan, 27, had initially told reporters he didn't understand Greipel's ire.

"Greipel was angry with me but I don't know why, you'd have to ask him," said Sagan. 

But those watching television pictures had no doubt about what they'd seen.

"I've now been able to watch the replay of the sprint a few times. Sagan deserves DQ on that one. Hope @MarkCavendish is ok. That was heavy," Australian Robbie McEwan, a former cyclist and top sprinter himself having won 12 Tour stages, said on Twitter.

Sagan had originally finished second to stage winner Arnaud Demare of France, which would have moved him up to second overall thanks to a six-second time bonus.

However, he will now take no further part in the Tour.

It means the sprinters' green jersey, which Sagan dominated in each of the last five years, is now up for grabs.

Demare leads the race thanks to 50 points for winning the stage.

He said the race jury had "shown guts" in punishing the world champion.

"Now I've got a chance for green," he added.

He leads the competition with 124 points with previous holder Marcel Kittel, who was held up by another crash in the final kilometre and couldn't contest the sprint finish, second on 81 points.

Sagan had been bidding to match German Erik Zabel's record of six green jersey victories.