Japan's rugby association on Friday indefinitely suspended national side winger Christian Loamanu after the Tongan tested positive for marijuana.

His team, top-ranked Toshiba Brave Lupus, said they would pull out of the upcoming national championships as an act of atonement.

"On behalf of the Japan Rugby Football Union, I apologise to the entire rugby community for this unfortunate incident," said the union's chairman, Noboru Mashimo.

"Prohibited substances have no place in the world of rugby," he said.

Loamanu, who played for Japan in the 2007 World Cup, had tested positive for using cannabis after an earlier random test but denied the charges. However, rugby authorities said he had tested positive again.

Rugby officials said the Tongan continues to deny he used the drug, arguing that he may have consumed it by accident after being given a cigarette by unknown people.

Toshiba Brave Lupus, affiliated with electronics giant Toshiba Corp., said it would pull out of the national semi-finals because of the case.

Marijuana is taboo in Japan, which strictly forbids both hard and soft drugs.

Japan's traditional sport of sumo has also been rocked by marijuana allegations, with three Russian and one Japanese wrestlers ousted over its use.

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