A HONG KONG listed company has made a public statement clarifying its relationship with an entertainment firm controlled by two of the Heung brothers. Mandarin Dragon Holdings made an announcement last week stating that its exposure to a joint venture involving Win's Music and Video Enterprises is limited to $15 million. The clarification is the second made by Mandarin Dragon on the issue. It was made at the request of the stock exchange. Win's Music and Video Enterprises is controlled by Jimmy Heung Wah-shing and Heung Wah-keung, who are extremely active in the local movie industry. In the announcement the company restates that its core business is pharmaceuticals and real estate development. It says that the joint venture with Win's is ''in the best interests of the company''. It adds that the joint-venture company had not requested additional financing from its shareholders and Mandarin Dragon had no current plans to lend money to the joint-venture. It has been reported in the Hong Kong Economic Times that the joint-venture, which was established in April, would open up to 100 video and mini-cinema shops in China this year. Mandarin Dragon pledged to review the status of its investment in the joint-venture from time to time. In a completely separate development Jimmy Heung was detained last week by Independent Commission Against Corruption officers as part of a continuing investigation into alleged tax evasion by members of Hong Kong's film industry.