"Today, our teammate and friend Wouter Weylandt passed away after a crash on the third stage of the Giro d?Italia," said Leopard-Trek Manager Brian Nygaard.
"The team is left in a state of shock and sadness and we send all our thoughts and deepest condolences to the family and friends of Wouter.
"This is a difficult day for cycling and for our team, and we should all seek support and strength in the people close to us."
Weylandt, 26, was left bloodied and unconscious and requiring a cardiac massage after a crash which occurred on the descent of the Bocco mountain pass around 25km from the finish line.
Race officials later claimed his left pedal got stuck in a wall at the side of the road, forcing Weylandt to tumble around 20 metres to the ground below.
He received emergency medical treatment by race doctors and was scheduled to be airlifted to hospital but had to wait as an emergency helicopter looked for a suitable landing spot.
The head doctor on the race Dr Tredici said they had battled in vain to save Weylandt's life.
"We were in the car behind the peloton. We arrived around 30 seconds after the accident but even then there was little we could have done. It was a very serious case," he said.
"A few minutes later the ambulance with the CPR equipment arrived and we tried to bring him back to life."
"His heart has stopped beating," announced Auro Bulbarelli, the head of sport for RAI television who first broke the tragic news.
Weylandt, who spent the bulk of his career with the Belgian team Quick Step after turning professional in 2006, won the third stage of the race last year, in Middelburg (Netherlands).
He joined new Luxembourg outfit Leopard-Trek, the home of Australian Stuart O'Grady and the Schleck brothers Andy and Frank, at the start of the season.
Weylandt is the first rider to die in a crash while racing since Kazakhstan's Andrei Kivilev succumbed to head injuries the morning after a crash on the second stage of Paris-Nice.
Kivilev's death, while the rider was travelling at a seemingly innocuous speed, signalled the introduction of the mandatory wearing of helmets in the professional peloton.
Weylandt, who hailed from Ghent, is the first fatality on the Giro since 1986 when Emilio Ravasio crashed on the first stage and fell into a coma to die several days later.
Although life and career-threatening crashes are a regular occurrence in cycling, the last fatality on the world's biggest race, the Tour de France, was over a decade ago.On the race's 15th stage in 1995 Italy's Fabio Casartelli -- a member of Lance Armstrong's Motorola team -- died a few hours after sustaining injuries in a crash on the descent of the Portet d'Aspet in the Pyrenees.
Following the tragedy race organisers cancelled the post-race ceremony in Rapallo, where Spaniard Angel Vicioso, of the Androni team, won the stage ahead of new race leader David Millar of Britain (Garmin).