The positive test came after stage five of this year's Tour

The rider will remain unnamed pending investigation, but UCI spokesman Enrico Carpani said it was not a top cyclist.

"It's a second-tier rider - not Lance Armstrong or Robbie McEwen, nor any of the leading riders," said Carpani.

The unidentified rider tested positive for norpseudoephedrine on 6 July after the fifth stage, which McEwen won.

Norpseudoephedrine, also known as cathine, is related to pseudoephedrine, an ingredient in Sudafed and other over-the-counter cold remedies.