A Japanese politician has demanded an inquiry into allegations the vice-chairman of Japan's Olympic Committee has close ties with the Yamaguchi-gumi, Japan's largest yakuza group. Yoshio Maki, a member of the opposition Japan Restoration Party, on Wednesday asked the education minister in parliament whether he was aware of the photo that shows Hidetoshi Tanaka, who is also chairman of the elite Nihon University, sharing drinks with Shinobu Tsukasa, the head of the gang. Two reporters reportedly had their kneecaps smashed by assailants last year when they started investigating the photo. The minister, Hakubun Shimomura, replied that he had been unaware of the allegations of a link between Tanaka and organised crime, but added that he intended to look into the matter. "I have spoken to officials at the university who said they were shown the photos of Tanaka with a yakuza boss by Tanaka himself, who was using the photos to intimidate them and to warn them of the consequences of opposing him," Maki told Vice News . "They are afraid for their lives and afraid to oppose Tanaka for fear of what will happen to them. I believe the photos are real." Preparations for the 2020 Tokyo Olympic Games come under the purview of the ministry of education, while there are numerous lucrative contracts being drawn up for new facilities and infrastructure for the event. Some estimates put spending for the Games at US$50 billion, while Japan's 21 organised crime groups are generally understood to take a cut of around 5 per cent of all revenue from the nation's construction industry. That vow to look into the matter is the first solid commitment by the government to look into a link that has been rumoured since early last year, said Jake Adelstein, author of Tokyo Vice: An American Reporter On The Police Beat In Japan and an expert on Japan's underworld groups. "Tanaka has long been rumoured to have links with organised crime, although Nihon University has always tried to brush the allegations under the carpet by saying that while he may have met members of crime groups by chance in the past, he had nothing to do with them any more," Adelstein said. "The photo was sent anonymously to a lot of press in Japan all at once, but none of them would print it because, to be honest, they were scared." Tanaka is very close to Prime Minister Shinzo Abe and Nihon University also wields considerable influence. The media was apparently given a demonstration of the consequences of running the photo in September last year when two reporters for the Keiten Shimbun were assaulted when they started asking questions about the image and indicated that the paper was planning to print it. Both men had their kneecaps broken and phone calls were made to other publications to warn them that their reporters could expect similar treatment if they went ahead and published the photo. "No one has wanted to touch the story so far because they don't want their reporters to get hurt, but now that the photo is out there and questions are being asked in the Diet, it will be harder and harder for them to ignore it," Adelstein said.