PROPERTY companies with large land banks in Kowloon will be the major beneficiaries of the new plot ratio zones announced last week by the Town Planning Board. Sun Hung Kai Properties, Henderson Land, Sino Land, Shun Tak and Lai Sun Development have all been active buyers in parts of Kowloon where the new zoning ratios have come into effect. Designed to stimulate redevelopment in Kowloon, the revised plot ratios will increase the available area on each site that can be used for the construction of buildings. Sun Hung Kai Properties and Sino Land are expected to make large gains as both have recently purchased industrial sites in Kwun Tong and Kowloon Bay, two of the areas which received the largest plot ratio gain. Property companies less well positioned included Cheung Kong and New World which have not been as aggressive in the areas awarded higher plot ratios. Hong Kong Real Estate Agents' president Michael Choi said residential sites that received higher plot ratio gains in Mongkok, Shamshuipo and Hunghom will benefit more from the zoning relaxation than sites in other areas. Under the new regulations, about 79 per cent of residential sites, 89 per cent of industrial sites and 31 per cent of office sites in Kowloon and areas south of Boundary Street will have a higher or equivalent plot ratios. ''No one knew for sure when the zones would be announced, but there has been a lot of buying activity in anticipation of the changes,'' said Nomura Research Institute (NRI) manager Nicholas Pang. He said the recent relaxation of height restrictions in certain parts of Kowloon was the cue that the ratio changes would soon be announced. ''The value of sites owned by developers in areas re-zoned will rise,'' Mr Pang said. He expected New World, Cheung Kong, Sino Land and Hang Lung to follow Sun Hung Kai and Henderson Land in the race to develop sites in Kowloon. The revised ratios will only apply to new building plans and the areas included in the parcel of land affected by the change include Mongkok, Ma Tau Kok, Shamshuipo, Kowloon City and Hunghom. Past attempts to redevelop old Kowloon sites have been hindered by the limited size of buildings and the time-consuming process of individual negotiations with flat owners. ''Even with their new plot ratios, many of the Kowloon sites will still be small projects,'' said Swiss Bank Corporation analyst, Adrian Ngan Wai-hung. ''Titles are scattered because so many of the buildings are old and this combined with the small scale of development will make a lot of the projects more appealing to small-and medium-size property companies.'' Mr Ngan said there would be some exceptions but big property companies would continue to focus on major residential projects in the New Territories and on acquiring new sites at land auctions. Gains for commercial sites in Tsim Sha Tsui and along Nathan Road are expected to be minimal because the new plot ratio of 12 is only marginally higher than the previous building limitation. Richard Ellis director Dominic Leung said it would be several years before the full impact of the higher ratios was felt, but ''an immediate increase in values will be recorded in key areas, especially those where there has been a substantial increase inthe plot ratio zonings,'' he said.