Few lenders, and no large bank, has cut variable interest rates on home loans in New Zealand in the two weeks since the RBNZ cut the official cash rate by 50 basis points to 2.5 per cent.There have been some adjustments to fixed rates by banks, including the promotion of very short-term fixed-rate offers.Reserve Bank deputy governor Grant Spencer said yesterday he would like to see more competition between banks in the area of floating mortgage rates, where margins to the OCR were the highest he had seen."We do see a considerably higher margin on floating rate mortgages than on most fixed rate mortgages, so in our view there's probably more scope for competition in the floating rate mortgage segment of the mortgage market."Those margins are as high as I can recall on the floating rates," he said."The OCR reduction at the end of April had some impact. A couple of banks reduced rates, not floating rates. Bank bill rates are down so a lot of the business lending rates are down," Spencer said."It's fair to say we have been disappointed with the response to date, but the OCR-retail rate relationship is not a precise one. Sometimes the lags are long and there are other factors affecting the actual mortgage rates other than the OCR and we have to acknowledge that," he said."We may see further reductions in mortgage rates as some of those other conditions in the markets change. We're not considering at this point changing our policy approach or introducing any unconventional instruments that we have seen in other countries." Interest.co.nz