Charly Wegelius has received a 15-day ban after failing a blood test.
Wegelius must undergo more tests
The De Nardi Colpack rider was not allowed to start the Tour of Lombardy World Cup race.
Wegelius was tested a few hours before the start of the race and found to have a blood haematocrit level - the ratio of red blood cells to the total volume of blood - above the 50% limit allowed.
He was declared unfit to race under International Cycling Federation (UCI) rules.
The UCI said there will be no other sanctions for the 25-year-old other than the short ban.
Wegelius was a member of the British team that took part in the world road racing championships in Hamilton in Canada last Sunday.
He did not finish the race due to illness.
Elevated red blood cell levels can occur naturally under certain circumstances but can also indicate the use of EPO - a banned artificial hormone that increases an athlete's aerobic ability.
Wegelius said he has never taken EPO.
"I don't want to say anything because it will only make things worse. Ask Aldo Sassi
(Wegelius's former coach when he rode for the Mapei team). He knows I've never done EPO," Wegelius told Reuters.
In a press release the De Nardi Colpack team said Wegelius' haematocrit value fluctuated as a consequence of the removal of his spleen following a motorbike accident in 1998.
The team added that Wegelius will go the UCI headquarters in Switzerland on Monday to undergo a series of tests.