The Japan Broadcasting Corporation, known as NHK, has banned five popular singers from appearing on its TV and radio networks.

The five singers of Japanese traditional ballads were denied further appearances because they are accused of participating in a golf tournament and party that celebrated the birthday of a well-known organized crime boss.

NHK spokesperson Ryoji Ito told Billboard.biz: "Takashi Hosokawa, Akira Kobayashi, Nobue Matsubara, Hiroshi Kadokawa and Kiyoshi Nakajo not only took part in the golf tournament, they also performed at the gang leader's party."

Of the five singers, Takashi Hosokawa is by far the most popular in Japan, having appeared on the NHK network's showcase year-end special 37 times.

"We contacted their management companies," Ito continued. "They confirmed all the entertainers mentioned had participated in the tournament and performed."

It has been 22 years since NHK, the national public broadcaster, has taken such a step. In 1986 NHK banned the massively popular crooner Saburo Kitajima for participating in a New Year'a party with organized crime leaders.

Calls to the management companies of the banned singers went unreturned.