The German Cycling Federation (BDR) said Vogel, 27, crashed while training on a track in Cottbus and is now being treated in a Berlin hospital.

"She sustained a severe spinal injury during the fall and receives intensive medical care," the BDR said.

"Vogel collided at full speed with another racer. She will be operated on in the next few hours."

Vogel, who also works as a part-time police officer in her native Germany, won gold in the team sprint in the London 2012 Olympics and in the individual sprint in Rio four years later, when she beat Britain's Becky James.