A scandal-stained Russian sumo wrestler has threatened to blow open a catalogue of “evils” surrounding Japan's most traditional of sports in a move that could destroy the reputation of many of its biggest stars.

In an incendiary public statement, which his lawyer is understood to have strongly advised against, the former high flier lashed out at the entire structure of the sport, alleging that it was riddled with match-fixing and other problems.

The extraordinary outburst comes as sumo is fighting a last-ditch battle to save its name with the Japanese public, and to win back audiences turned off by a seemingly endless run of scandals and debacles. The public airing of grievances also shatters the long-cherished tradition that sumo wrestlers should be models of laconic silence and forbearance.

The disgraced Soslan Gagloev, who fought under the name of Wakanoho until his lifetime ban last month for marijuana possession, said that he stood ready to lift the lid on a “dirty world” of rigged bouts and drug abuse within the sumo elite.

“I was forced to accept money and made to fight in unfair matches from the very moment I entered the makuuchi [the top rank of sumo wresting].

Warning that he would reveal “other evil things that I know” later in court, the 20-year-old Russian had one last swipe at the sport from which he was so abruptly disbarred: “my stable master and others knew about the match-fixing but nobody stepped in because they had also been fighting in rigged matches themselves,” he said.

When he does have his moment in court, Gagloev is expected to repeat the allegations made today and expose many of his stable-mates as habitual users of marijuana. He did not identify people by name, but indicated that he was prepared to do so in a more formal legal setting.

That setting will be the ongoing court battle between the publisher of the magazine Weekly Gendai on one side and the Japan Sumo Association and Mongolian grand champion Asashoryu on the other. The magazine is being sued for libel after alleging that the sport was blighted with match-fixing, though legal experts believe that Gagloev's testimony will dramatically alter the direction of the case.

Although allegations of match-fixing and drug abuse have been swirling around sumo wrestling for some years, the Russian's plans to testify in court have sent a thrill of horror through the already chaos-stricken sport. It is not just that the lid has finally been lifted on Japan's national sport, but that the exposure has come at the hands of a foreigner.

This time, one veteran sumo journalist tells The Times, the potential damage of the allegations could be huge: a code of silence that has protected the sumo from the worst of its scandals has been broken and anything could happen in the wake of that. Until now, nobody from within the system itself has ever stepped forward to expose what goes on behind the closed doors of the training stables or at the opaque management level of the sport.

But many believe that sumo may now be fatally tarnished. Wakanoho's ban from the sport was followed just days later by the discovery of traces of drugs on two other Russian wrestlers, the brothers Roho and Hakurozan. The trio of ejections prompted the unprecedented resignation of Kitanoumi, one of the greatest champions of all time who stepped down as head of the sumo association to take responsibility for the scandal.

Japanese audiences have already begun to feel considerable disgust with the sport after the death last year of a young trainee wrestler who was effectively beaten to death with bottles and baseball bats during a practice session.

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