Ivan Basso has been suspended by his Discovery Channel team after the Italian Olympic Committee reopened its probe into a Spanish doping scandal.
Basso signed a two-year contract with Discovery in November
Basso must attend a hearing on 2 May on charges of having used or attempted to use a banned substance or method.
The Italian was banned from last year's Tour de France after being implicated in "Operation Puerto" although the charges against him were later dropped.
The former CSC rider signed a two-year contract with Discovery last November.
Basso was one of 50 riders caught up in last year's Operation Puerto after his name was linked to a Spanish doctor accused of running a blood doping clinic in Madrid.
We continue to stand behind Ivan and intend to cooperate with all parties involved until there is closure
Discovery Channel team manager Johan Bruyneel
He was cleared of involvement by the Italian Olympic Committee and the Italian Cycling Federation in October, and has always maintained his innocence.
A Discovery Channel statement said Basso had been suspended "pending further information in a new investigation coming out of Italy".
General manager Bill Stapleton added: "We have requested that Ivan not race until we receive more information and this issue has been resolved."
Discovery sports director Johan Bruyneel said: "We continue to stand behind Ivan and intend to co-operate with all parties involved until there is closure.
"I have spoken to Ivan and although frustrated he agrees and understands with the decision we have taken."
Basso is a Giro d'Italia winner and was second to Lance Armstrong - who part-owns the Discovery Channel team - in the Tour de France in 2005.