Barbara Jerschina, a doctor who treated the Deceuninck-Quick-Step rider, told the naszosie.pl website that Jakobsen had been placed into a medically-induced coma after sustaining a substantial loss of blood, a cerebral cranial injury and a broken palate.

Jakobsen was sent crashing into the barriers in the final metres of the stage in Katowice after colliding with compatriot Dylan Groenewegen.

"Jakobsen has extremely serious injuries and his life is in danger," Jerschina said.

"We did everything that could be done, but the situation was difficult. 

"It was difficult to intubate as he has a very serious cerebral cranial injury and a broken palate but larynx was able to be supplied with oxygen all the time and his heart was working well."

In a statement, the Deceuninck-Quick-Step said Jakobsen's situation "is serious but at the moment he is stable".

"Because of the gravity of his multiple injuries he is still kept in a comatose condition and has to remain closely monitored in the following days at the Wojewódzki Szpital," the team added.

The International Cycling Union (UCI) said Groenewegen had caused the crash with his "dangerous behaviour", which it said it "strongly condemned".

Groenewegen, who has been disqualified, could face further sanctions after the incident, which led to several other riders, some of whom were taken to hospital, crashing at the conclusion of the stage.

"The UCI strongly condemns the dangerous behaviour of rider Dylan Groenewegen (Jumbo-Wisma), who sent Fabio Jakobsen (Deceuninck-Quickstep) into the barriers a few metres from the finish, causing a collective crash at the end of the first stage of the Tour of Poland," the UCI said in a statement.

"The UCI, which considers the behaviour unacceptable, immediately referred the matter to the Disciplinary Commission to request the imposition of sanctions commensurate with the seriousness of the facts."

Groenewegen led a bunch sprint in the closing metres but faced competition from Jakobsen, with the Deceuninck-Quick-Step rider aiming to overtake on the finishing straight.

Jakobsen crashed into the barriers after Groenewegen moved to the right.

Groenewegen, who rides for Jumbo-Visma, crossed the line first before falling in the aftermath of the collision with Jakobsen.

The race website currently lists Jakobsen as the stage winner in a time of 4 hours, 31min, 50sec.

France's Marc Sarreau and Luka Mezgec of Slovenia are listed as completing the top three on the same time.

The stage began at the Silesian Stadium in Chorzów and saw riders complete a hilly 195.8 kilometre route to Katowice, where the race concluded in the bunch sprint.

Day one of the race also marked the first anniversary of the death of Belgian rider Bjorg Lambrecht, who crashed at last year's race.

The 22-year-old crashed on stage three of the 2019 Tour de Pologne after falling into a concrete culvert, with the cause of the incident still unknown, and later died in hospital during surgery.