ELDERLY people can expect to buy urban flats at a high discount if the Housing Society's proposal to offer purpose-built blocks for senior citizens is approved. The proposal has been prompted by a trend in recent years for more elderly couples to live on their own after their children have married or emigrated. The society is identifying sites in the urban areas to build high-rise blocks specially designed to suit the needs of elderly residents. Warden service may also be provided. Those over 60, and able to pay the mortgage will be eligible, according to society chairman Ronald Poon Cho-yiu. The society has not gone into details of management or marketing, but initial ideas are to follow the example of the Housing Authority's home ownership scheme and offer flats at an average of 30 per cent discount to market values. Mr Poon said the flats could be as cheap as $600,000 and would probably be very small. The re-sale of flats would be restricted to elderly people in the contract with owners. ''Our concept is to build senior citizen homes where the elderly residents can make a lot of friends of similar ages in their neighbourhood. Similar projects are popular in the United States and Canada. ''The only problem is the availability of cheap land in the urban areas. ''We have to seek support from the Government first before we can go a step further,'' Mr Poon said. The proposal has been submitted to the Planning, Environment, and Lands Branch for consideration. Officials are understood to have raised concerns about potential problems when, in case of emergency, thousands of elderly people would need to be evacuated. Veteran social welfare worker Professor Nelson Chow Wing-sun said: ''From a social welfare point of view, it is not very suitable to have too many old people living in one area.'' The vice-chairman of grassroots group, Hong Kong Association for Democracy and People's Livelihood, Leung Kwong-cheong, said: ''I do not believe the idea will work. ''You sell the flats to elderly buyers only. But are you going to restrict them to re-sell the flats to, say, their children or anyone else for making money? ''I suggest the society rent out the flats so that they can have more control over the management.'' The society's feasibility study on building flats in Shenzhen for the elderly here is expected to be finished by next month. The society has built a total of 745 flats in six estates in Hong Kong for the elderly and is working on a scheme to provide housing for the single.