Guardiola urges Contador to fight ban

"In these situations, and I speak a bit from personal experience, there is only one person who knows what happened, that is him," Guardiola said in comments replayed in Spanish media.

"And if he knows that he really is innocent as he says publicly and privately, he should defend himself until the end of the world and for as long as it takes. The truth always comes out in the end."

Guardiola was speaking at a press conference on the eve of Barcelona's King's Cup semi-final second leg against Valencia on Wednesday and his comments were published in sports dailies including Mundo Deportivo.

The Catalan coach was banned for four months after he tested positive for nandrolone in 2001 while playing for Italy's Brescia but he was cleared by a criminal court on appeal in October 2007.

The Switzerland-based Court of Arbitration for Sport banned Contador for two years following a positive test for the banned substance clenbuterol.

Contador said his lawyers were looking into a possible appeal, which must be lodged within 30 days. He argues he is the victim of a contaminated steak eaten during the 2010 Tour de France

"My lawyers are looking into all the possibilities. We will continue to fight until the end," he told a packed news conference in his hometown of Pinto just south of Madrid.

Backdated to August 2010, when he announced the news of his positive test weeks after his third yellow jersey triumph, the ban means Contador can return to competition on August 6, 2012.

As well as ruling him out of this year's Tour de France and the Olympic Games in London, he will be stripped of several wins including his 2010 yellow jersey which will now be handed to runner-up Andy Schleck of Luxembourg.