Shinsuke Shimada, 55, retired from the entertainment industry after it emerged he had exchanged text messages with a gang member, his agency said on its website.

"These exchanges indicated a certain amount of closeness between them," said Yoshimoto Kogyo Co.

"Such activity involving a personality on TV or in other media which have a great social impact cannot be condoned for any reason."

The sharp-tongued comedian hosted six popular TV shows every week, including a programme to rate privately treasured antiques.

His exit has shocked the country's television industry, although there is a long history of rumours connecting Japanese mobsters with entertainers.

At a hastily arranged news conference late Tuesday, Shimada bowed deeply in apology and admitted he had known the unnamed gangster since being saved from unspecified "personal trouble" more than 10 years ago.

"We have met in person just four or five times as we were aware that entertainers and crime syndicate members should not mix," Shimada said.

He said he had not paid the yakuza for his help in solving the trouble which, according to reports, came after he was intimidated by another gang for having ridiculed a right-wing group on his talk show.

"I felt indebted to him. I thought it was safe to remain associated at this level," he said.

"I have tumbled down from the top of the mountain down the cliff but I think it is typical of me.

"I will become an ordinary person from tomorrow. I want to live quietly."

The news conference was held as a popular weekly magazine prepared to publish an article on Shimada's yakuza connections.

His associate was identified by Japanese media as the head of an Osaka-based gang affiliated to the Yamaguchi-Gumi, Japan's biggest crime organisation.

Shimada, known for his straight-talking style, has long been controversial. In 2004, a court fined him 300,000 yen ($3,900) for punching and injuring one of his agency's female employees.

Shimada started his showbiz career in 1977 as part of a duo, helping to whip up a boom in "Manzai" stand-up comics across the country.

He went solo in 1985, becoming a fixture on evening television.

Even Japan's top government spokesman, Yukio Edano, commented on the case.

"It was unavoidable as the government has been strongly promoting efforts to eliminate organised crime," Edano said.

"Mr. Shimada has been loved by the people because of his genius. It is unfortunate that such talent has been cut down this way."

Copyright AFP (Agence France-Presse), 2011