I REFER to the letter headlined, ''Postage hike uncalled for'' (South China Morning Post, April 9) from your reader Mr Hinrichs. Since postal charges were last revised on April 1, 1991, operating costs have risen significantly in the past two years. In order to maintain the real value of these charges, it will be necessary to introduce a revision sometime in the current financial year. Although it is estimated that the Post Office will make an overall profit in 1992/93, I must point out that certain services suffer losses, such as, the local letter mail. This loss will increase as operating costs increase in future. It is not realisticin the long term to depend too heavily on our profitable services to subsidise those loss-making ones. Details of the revised postal charges have not yet been finalised. However, Mr Hinrichs can rest assured that advance notice will be given once we are in the position to do so. K. C. CHAN for Postmaster General
