Former Tour de France champion Jan Ullrich insisted Sunday that he is above reproach despite blood bags seized in a Spanish doping scandal having been proven to be his by German prosecutors.

DNA tests on blood seized in the offices of Spanish doctor Eufemiano Fuentes last year have proven that the samples are Ullrich's, say Bonn prosecutors, who are investigating the rider for possible fraud.

But in a letter addressed to his fans on his website, the 1997 Tour de France winner said: "These latest findings change strictly nothing of the fact that I'm blameless.

"I've never lied to anyone thoughout my career nor used anyone so I can't admit to an error that I have not made. I fear no procedure, no prosecutor, or federation.

"For me as well there are still a lot of questions which remain unanswered and until everything is cleared up I'm no longer going to comment publicly on this case."

Ullrich added that he would give his own version of the facts at the right time.

"Of course it's not an easy time because the situation is out of the control of me, my friends and family. Life is a battle which I'm ready to wage," he added.

Ullrich retired from cycling in February, 10 months after his name surfaced in Operación Puerto, leading to the German being excluded from last year's Tour de France race and sacked by T-Mobile.