The Bora-Hansgrohe cycling team was excluded from the Belgian E3 Saxo Bank Classic on Friday after one of its riders returned a positive Covid-19 test.
In a statement the German team said that British rider Matthew Walls had tested positive.
"After Walls' positive test result was received and confirmed by a second test, several PCR tests were carried out on all other team members yesterday, all of which were negative," the statement said.
'I just didn't have it' - GB's Thomas reflects on disappointing Olympics
- 'Really good for morale' - Thomas surprised by early form for Ineos
- 'He almost doesn't need to train' - Pidcock's early success is unique, claims Ineos coach
- Tour de France organisers confirm Bilbao 2023 Grand Depart
"Despite this, according to the instructions of the Belgian Cycling Federation, the team is not allowed to take part in today's race."
The race is part of the build-up towards the Tour of Flanders which takes place on April 4.
In a separate race, Spanish team Kern Pharma said on Friday that they were leaving the Tour of Catalunya following two positive cases within their squad.
'How the f*** does he know who I am?' - Wiggins shares stories about Armstrong and Cipollini
‘What have I done in a previous life?’ - Thomas after another crash at Olympics
Opinion: Van Aert, Pogacar and a golden age of superstars in Tokyo