MORE than 6,200 cases of property speculation have been uncovered by the Government since amendments were made to the Stamp Duty Ordinance last year. The Inland Revenue Department (IRD) discovered transactions with a total of about $1 billion chargeable to profit tax under the ordinance. The Government revealed the figures yesterday to support its request to legislators to extend the ordinance for another two years from January 1, next year. The Government said the ordinance was effective in both curbing property speculation and identifying speculative activities. The amended ordinance imposes a stamp duty on all sales agreements of residential property. It also requires information to be provided in the sales agreements which enables the IRD to identify speculative property transactions. The Government can tax the profit of a property transaction that is proved to be of a speculative nature. The Government said in a paper given to legislators ye sterday that there were more than 6,200 such prima facie cases, in which resales had taken place either prior to or shortly after the execution of assignment of property. The Government said details of the sale would no longer be revealed if the amended ordinance lapsed after its original validity period of two years. ''If the legislation were to expire, the useful data collection channel for profits tax purposes would be lost,'' the paper said. ''We estimate that the consequential loss of revenue would be at least $60 million a year.'' The amended ordinance also provided for stamp duty to be charged on all agreements for sale of residential property, which the Government has found effective in curbing speculation. Before that, stamp duty was only payable on completion of the transaction. ''Taking the period since the enactment of the amendment ordinance in January 1992 as a whole, the property market has remained buoyant. ''But the extent of property speculation has to a certain extent been contained,'' the paper said. ''There is considerable risk that if the relevant stamp duty provisions were not extended beyond midnight on December 31, 1993, speculation might become rife again to the detriment of genuine home-buyers,'' it added.