A TAX scandal involving Japan's top sumo idol and other members of his wrestling family has added to woes including allegations of corruption and drug taking already afflicting the traditional Japanese sport.

In the latest smear on sumo, tax authorities swooped on Takanohana (23), the reigning "yokozuna" or grand champion, asking him why he failed to report income of 68.7 million yen (£395,000) from 1993 to 1995.

It is the first time tax authorities have conducted a probe against a yokozuna, who are normally accorded the utmost respect.

The raid took the shine off Takanohana's winning of his 14th tournament title on Sunday.

"I was shown by national tax authorities how to correctly pay my taxes, and I will follow their recommendations from next year," Takanohana said in a terse statement on Tuesday after paying back taxes and fines.

The tax scandal comes on the heels of allegations by a retired sumo star that the industry is rigged. The former wrestler, Onaruto, said many wrestlers fixed matches in advance.

According to Onaruto, some wrestlers "sell" their matches to young, aspiring grapplers or those in danger of demotion at prices of about 600,000 yen a bout.

Not only were wrestlers involved in match fixing, Onaruto alleged. He said the entire sumo world had shady ties with mobsters, including drug and sex connections.

The tax probe was apparently a warning to the entire sumo world, a sumo association source said.

"We must take this seriously because it was the stable, and not just one wrestler, which was targeted," the source said.

The surprise tax investigation also targeted members of Takanohana's family, one of the most successful sumo stables in the post war period.

His elder brother, "ozeki" or champion Wakanohana (25) also came under fire for not reporting 9.3 million yen and their father stable master Futagoyama, was accused of failing to report 300.6 million yen.