THE volume of property transactions in Hong Kong leapt a staggering 21.2 per cent month-on-month in February and 49 per cent year-on-year, according to figures released yesterday. Genuine home-buyers rushed to make mortgage down payments with bumper Lunar New Year bonuses, a surge in mainland Chinese buying, and speculators enjoying another field day. In all, about 13,024 sale and purchase agreements were registered with the Government during the month, involving a total $54.87 billion, the great bulk of which was spent on flats. The resurgence in sales activity pushed prices up significantly across the board, but by just how much is still difficult to determine. ''These figures show the tighter mortgage restrictions implemented by banks are not having a huge impact here on activity,'' said property analyst and managing director of Morgan Stanley Asia, Peter Churchouse. Banks' new mortgage approval figures for December and January, announced last month, had served as a warning of what was to come. Alarm bells started ringing in the Hong Kong Monetary Authority a few weeks ago when it was discovered the volume of new mortgages approved but not yet drawn surged a startling 71 per cent in January - despite banks' ever-tightening mortgage-lending policies. About $6.5 billion of new mortgages were lined up by Hong Kong's big banks in January for potential buyers, as speculators and genuine end-users armed themselves with loan facilities, ready for the expected post-Lunar New Year market rally. This was the highest level of new home-loans approved since the big residential market surge last July and enough to spur the Monetary Authority's deputy chief executive for banking, David Carse, to send out a caution to banks. Try as they may, Hong Kong's big banks seem unable to drive speculators out of the dangerously spiralling residential property market, particularly at the top end where buyers tend to be less dependent on the banks for home financing. The problem of persistent local speculative buying has been made worse by a resurgence in mainland Chinese activity. Beijing has had little success with its bids to slow down the amount of money being hedged by mainland corporations in Hong Kong real estate. On Thursday, Lu Ping, director of the Hong Kong and Macau Affairs Office, hinted that mainland-funded firms would be barred from speculating in property in the territory to prevent them from contributing further to soaring prices. Should Beijing take this stance, it is likely to enjoy only limited success. Raymond Ngai, an analyst at Mees Pierson Securities, doubted whether Beijing could effectively curb the flow of money into the property market by Chinese-owned companies. He said many such firms were not directly controlled by Beijing authorities and were financially strong enough to continue making deals. ''As 1997 approaches, it is inevitable that more and more Chinese companies would want to come to Hong Kong to start their business here, and a logical step is to buy their own office space,'' said Mr Ngai. Over the past year, Chinese interest has been centred mainly on the luxury residential and office strata-title sectors. In recent weeks, the focus of mainland buying appears to have been changing. Property analyst Michael Green, a director of S G Warburg Securities, said since Hong Kong's big banks announced a further crackdown on mortgage lending for luxury apartments in January, Chinese investors had become increasingly active in the mid-range flats market. Mr Green expected the overall volume of sale and purchase agreements to remain high in March, then gradually taper off to around 10,000 a month. While the figure is well off Hong Kong's record levels of 18,000 to 20,000 a month in 1991 and 1993, it is historically high. Until 1990, monthly sales and purchases averaged 5,000 to 7,000 transactions a month. Mr Churchouse believed Hong Kong's big banks would not ease liquidity until they saw a consistent period of 10,000 transactions a month over a sustained period.