Bjorg Lambrecht was taken to hospital in a helicopter following the crash which occurred around 96km from the end of the Chorzow to Zabrze stage.
Writing on Twitter the Lotto Soudal team said "The biggest tragedy possible that could happen to the family, friends and teammates of Bjorg has happened... rest in peace Bjorg,"
The organisers of the Tour of Poland race organisers said: "There are no words to describe this tragedy. Bjorg passed away following an accident on today's stage. Our thoughts are with his family, friends, team and the whole cycling community."
The young cyclist was resuscitated and taken to a hospital in critical condition. However, he died during surgery
There were conflicting reports of the seriousness of his condition following the crash, with the official race Twitter account announcing that Lambrecht "needed helicopter transport to a hospital following emergency resuscitation", while the race's live feed quoted "unofficial information" that "doctors managed to bring life functions back to Bjorg Lambrecht but his condition didn't allow for transportation by helicopter. He was taken to hospital by ambulance."
Lambrecht was an up-and-coming talent. He won U23 Liège - Bastogne - Liège race and came second in the Tour de l'Avenir, Giro Ciclistico della Valle d'Aosta Mont Blanc, Tour de Savoie Mont Blanc and Ronde de l'Isard in 2017.
He turned professional with Lotto Soudal last year. This season he finished just shy of the podium in La Flèche Wallonne, the Amstel Gold Race and the Brabantse Pijl. He also won the young riders qualification in the Critérium du Dauphiné, finishing the race 12th overall.
This year Bjorg Lambrecht extended his contract with Lotto Soudal by two more years in June.