Rudi van Houts' B-sample has also returned a positive result for banned substance Clenbuterol, and the Dutch cycling federation (KNWU) has suspended the mountain biker.
Van Houts's A sample tested positive immediately after returning from a trip to Mexico in late October, and the rider claimed that it was due to contaminated meat which he ate there. There have been several cases of Clenbuterol positives in recent months, amongst which the one of 2010 Tour de France winner Alberto Contador.
The Koninklijke Nederlandsche Wielren Unie announced that Van Hout was suspended until further notice. "The next steps will be the disciplinary procedure. The KNWU gives Van Houts the opportunity to prove his innocence," it said.
Van Houts is said to have been fired by his team, Mujltivan Merida. He is the reigning Dutch mountain bike champion.
The 26-year-old has said he will fight he charges. “I'm going to do everything I can to prove I am innocent,” he said, and has already given a sample for a hair analysis test.