The Beijing 2008 Olympic 50 kilometres champion is facing a life ban from the sport after testing positive for performance-enhancing drugs for the second time in his career.

But, while he admitted taking erythropoietin after testing positive the first time before London 2012, the 31-year-old claims he is innocent this time.

Schwazer tested positive for the anabolic steroid testosterone following re-analysis of a urine sample taken in January.

He claims the test was either tampered with or deliberately rigged to discredit him.

Last week, it was reported that Schwazer had taken his case to the Raggruppamento Operativo Speciale - a special unit of Italy’s national gendarmerie, the Carabinieri, set up in 1990 to coordinate investigative activities against organised crime.

It is now the main investigative arm of the Carabinieri dealing with organised crime and terrorism.

Schwazer's lawyer Gerhard Brandstätter has also demanded that his client's positive urine sample be tested for DNA.

He has alleged Schwazer could be the victim of "external interference" in the testing and claimed "everything that has happened probably happened because Alex went against strong powers and vested interests". 

The International Association of Athletics Federations provisionally suspended Schwazer earlier this month.

Schwazer appealed to Italy's National Anti-Doping Tribunal to have the ban lifted before Rio 2016, but they said they could not deal with the case before the Olympics are due to open on August 5.

But the Italian, who returned to competition following a three-and-a-half-year doping ban in May when he won the 50km at the IAAF World Race Walking Team Championships in Rome in May, says he wants to go to the Olympics and win.