Hamburg - Former Tour de France winner Jan Ullrich said the question of whether he was ever guilty of doping would be answered in a book he intended to write.
"These questions are not that easy to answer. Such things will be written about in a book which I will write for my fans and also for myself," he was quoted as saying in the Bild am Sonntag newspaper.
The 1997 Tour winner said that he would give himself as much time as he needed to write the book.
Ullrich suggested in the interview that not everything had been above board during his career.