THE value of a property can almost double in the space of a few months at the hands of speculators before it is ready for use, according to a leading property agent. After a unit has been sold, often with the property complex only a third completed, it can change hands six or seven times before an occupation permit is issued, said Charles Wheatman of Jones Lang Wootton. ''We have never seen such dramatic increases in prices in Hong Kong. The late 1970s was period of strong growth but not like this,'' he said. Over the past 12 months, the property market has been forced into a price spiral. It begins when the Government announces its land sales programme. Developers look at the site and check on building restrictions and what extra facilities must be built. These can range from car parks to sporting and education facilities. The price is based on projected property values and earnings potential, but due to the shortage of land and overwhelming demand the public auction process has pushed prices up sharply. Witness Sino Land which earlier this year paid a record $4.46 billion for two plots at Kowloon's Farm Road and Tai Po in the New Territories. This was equal to an accommodation value at Farm Road of $5,600 per square foot. Sino will have to sell its units for about $7,500 per sq ft to break even. Once the bidding is over, the successful buyer has to put down a deposit, usually about 10 per cent of the purchase price, immediately. Development plans are then submitted to the Government for approval before tenders are let for the building of foundations, followed by the above-ground work. According to Mr Wheatman, units can be pre-sold once the development is about 30 per cent complete and the developer can show it has sufficient finances to complete the project. A price list is drawn up and prospective buyers are invited to bid. Successful applicants are chosen by ballot. Once the unit has been sold it can become a free-for-all for speculators, according to analysts. The unit can change hands several times while it is still being built with Mr Wheatman estimating prices climbing by as much as 80 per cent. Climbing prices have made property investment an extremely attractive investment alternative for many people, especially since the stock market ran out of steam at the start of the year. Buyers have been able to make money through the property chain with stories emerging of speculators putting a deposit on a unit at pre-sales and being offered virtually double the size of their deposit to sell. The price spiral continues long after the unit is completed. Recent reports revealed that the price of one luxury property in Hong Kong jumped by $25 million in six weeks. Cheung Kong's $2.2 billion purchase of sites in North Point last week has given the first indication that prices may react to the Government's efforts to dampen the market, but analysts still believe prices will continue to push ahead this year.