BERLIN (AFP) - Germany's only Tour de France winner Jan Ullrich faces further investigation after finally admitting that he doped with the help of Spanish doctor Eufemiano Fuentes.

The 39-year-old Ullrich, who won the 1997 Tour de France, has told Monday's edition of German weekly Focus that he "had access to treatment from Fuentes", but insisted using no other substance than his own blood.

In April, a Spanish court jailed Fuentes for a year for performing blood transfusions on top cyclists.

"At that time, nearly everyone was using doping substances and I used nothing that the others were not using," Ullrich told Focus.

He now wants to put his doping past behind him, but Germany's Anti-Doping Agency (Nada) has already said it will investigate the matter.

"For the sport to be clean, it is important that he not only admits his crime, but also mentions the names of other participants in the background," Nada said in a statement.

The German's confession comes six months after former rival Lance Armstrong admitted doping throughout his career and was banned for life, as well as being stripped of his seven Tour titles.

Likewise, Ullrich's results have also been erased from the history books after finishing second to Armstrong three times in the Tour.

"We're both guilty. I am no better than Armstrong, but no worse either," said the German.

Having retired from cycling in 2007, all the while insisting he never cheated, Ullrich was found guilty of a doping offence by the Court of Arbitration for Sport in February, 2012.

He was retroactively banned that August, with all his results since May 2005 erased, but for many in Germany, his confession is too little, too late.

"For a truly credible confession, Jan Ullrich had his opportunity a few years ago," said Thomas Bach, president of the German Olympic Federation.

"He missed his chance and now, as far as I am concerned, he's trying to work with some rhetorical manoeuvres, which helps neither him nor the sport of cycling."

Long before Armstrong and Ullrich's doping admissions, the sport of cycling had a tarnished reputation in Germany with national broadcasters opting not to carry live Tour de France coverage.

Ullrich was barred from the 2006 Tour de France amid speculation that he had used illegal substances and Rudolf Scharping, president of the German Cycling Federation, said the confession should have come five years ago.

"It is far too late to try and clean things up," he said of the cyclist who retired in February 2007, denying that he had ever cheated.

"He could have helped the sport of cycling if he had laid everything out on the table much earlier. 2007 or 2008 would have been an appropriate time.

"He would have also been able to help himself, but now this is just the repetition of things long-since known, except this time they come from his mouth."