LESS money will be available to re-develop the Kai Tak airport site and revenues from land sales will be lost if there are delays in moving the airport to Chek Lap Kok, a Planning Department official warned yesterday. The Kai Tak site and adjacent Kowloon Bay, which will be reclaimed, will provide about 530 hectares of land which the Government has earmarked for residential, commercial, port and landscape uses. Present rough estimates are that the potential revenue from the site is more than $50 billion while the cost of developing the land is about $11 billion - excluding the cost of re-developing some parts of the site, which has not been worked out. Principal Government Town Planner, Dr Ted Pryor, said they had not anticipated a delay in moving the airport and did not know how much this might cost. But he said: ''The more you delay the relocation of the airport, the less money you have to spend on providing the land and services. On the other hand, you've not any revenues coming in. So on balance, I guess there would be some loss to the community.'' The present deadlock over Hongkong's future between Britain and China has cast uncertainty over completion of the Chek Lap Kok airport and the timing of the move from Kai Tak. Dr Pryor said China has not yet been consulted on the details of the redevelopment, although it agreed to broad proposals outlined in 1989 in the Metroplan. The Director of Planning, Dr Peter Pun Kwok-shing, said they were completing more specific proposals, such as one due in April on building densities in Kowloon which will consider whether height restrictions should be lifted. Dr Pryor said they were looking at areas where tall buildings might be allowed as visual breaks, although no firm decision on lifting restrictions had been taken yet. Redevelopment of other areas of Kowloon is also being planned and Dr Pun said they had drawn up scenarios for the region with and without Kai Tak airport. More housing will be part of any plans and Dr Pun said they would continue identifying urban sites for public housing, although these were difficult to firm up because many areas lacked adequate infrastructure such as drainage. Public housing tenants have complained they are being shunted to remote areas such as Tseung Kwan O and Tin Shui Wai, without adequate transport, recreation and other services. The wrap-up of Planning Department work in 1992 also touched on enforcement of amendments to the Town Planning Ordinance which were introduced in July 1991 to curb indiscriminate use of land. The conversion of fish ponds and paddy fields into container storage and other uses causes flooding and other problems and, although dozens of landowners have been notified of illegal land use, no cases have been taken to court. The World Wide Fund for Nature is particularly concerned because places earmarked as Sites of Special Scientific Interest have not been spared and the department has acted slowly on complaints. But Dr Pun defended their work, saying they needed time to identify landowners and to give them time to appeal to the Town Planning Board. He also said they had issued 477 warning letters in 63 cases, 78 enforcement notices for 20 cases and nine stop notices for three cases. Dr Pun also said they hoped changes to the Town Planning Ordinance, to be proposed later this year, would enable public consultation on urban land use under Section 16. Currently there is no provision for public input and residents in Jordan are upset that a historical site near them will be turned into high-rise apartments, without their being given the chance to raise objections.