TOKYO : Japan's legendary grand champion Kitanoumi quit Monday as head of the country's sumo association as two more Russian wrestlers were thrown out for allegedly smoking marijuana.

The scandal was the latest to tarnish the image in Japan of sumo, a heavily ritualistic 2,000-year-old sport whose athletes are expected to lead almost ascetic lives.

Kitanoumi resigned as head of the Japan Sumo Association after the scandal reached his stable, where one of the Russian wrestlers trained.

"I bear the responsibility," Kitanoumi, one of the greatest sumo wrestlers of the 1970s, told a nationally televised news conference.

"I am offering my resignation out of my own volition because I have troubled the Sumo Association and its fans. I must reflect deeply by myself," he said.

The scandal erupted last month when a Russian wrestler was arrested for marijuana possession, leading the sumo association to take the unprecedented step of expelling him.

In a bid to show it was an isolated incident, the sumo authority carried out surprise urine tests on 69 wrestlers -- but concluded that two more Russians, Roho and Hakurozan, had smoked marijuana.

Roho, 28, whose real name is Soslan Boradzov, and Hakurozan, 26, whose name is Batraz Boradzov, both flatly denied smoking marijuana. Hakurozan trains at Kitanoumi's stable.

Marijuana is strictly forbidden in Japan, and the case of the Russians has become a furore in Japan, where fans expect wrestlers to be role models focused on early-morning training and participation in ritual ceremonies.

Russia is among a growing number of countries that have virtually decriminalised marijuana, a soft drug.

Kokonoe, another former grand champion who serves on the sumo association's executive board, said that additional tests confirmed that Roho and Hakurozan both had smoked marijuana.

He said the board accepted Kitanoumi's resignation as chairman and appointed another grand champion, Musashigawa, as his successor.

Kitanoumi, 55, whose real name is Toshimitsu Obata, has been the chief of the 2,000-year-old sport since 2002.

He was monstrously strong in his peak days in the ring in the 1970s, and retains the record as the youngest wrestler to reach the top rank of "yokozuna" grand champion at the age of 21 years and two months.

But the sport's image has been seriously tainted in recent years due in part to the bad-boy antics of sitting Mongolian grand champion Asashoryu.

Its prestige fell further last year when a teenaged apprentice died after undergoing violent training by his stable.

Kitanoumi came under fire for defending sumo officials and not increasing the transparency of the sport, which is often seen as consisting as much of sacred rituals as athletic competitions.

- AFP/vm