THE stock exchange has refused to approve the prospectus of a company trying to gain a listing because it gave inadequate information on its mainland property interests. The move is an early indication of the increasingly tough line being taken by the exchange concerning disclosure on mainland property, fuelled by worries of volatile prices and unclear rules on land transfer. In the February issue of The Securities Journal , the exchange reports the case of an unnamed company told by the listing committee that its simple disclosure of the cash value of its China properties without any further information was not enough. ''The exchange decided that the names of the vendors and the acquisition cost of the properties in the People's Republic of China be fully disclosed in the prospectus,'' the Journal said. The exchange's concern comes at a time when listed companies are ploughing billions into China property projects despite some signs of a selective market slump, and is aimed at ensuring potential investors get a true view of listed companies' mainland property. The listing candidate was a property developer and investment company with substantial holdings in both Hongkong and the mainland. The candidate's draft prospectus said that 53 per cent of the company's revaluation surplus and more than 50 per cent of the 1992 net asset value was from mainland operations. As well as demanding greater financial data, the exchange demanded details of the vendors to see if they were related parties. It is unclear whether the listing candidate is prepared to proceed with its listing bid by agreeing to the exchange's demands. Concerns have been heightened by the move to invest away from neighbouring Guangdong province in places such as Dalian, Qingdao and Nanjing, where property rules are less clear. The exchange's interest is in making companies disclose the deals to help investors, rather than trying to regulate the deals.