With growth in lending to residential property investors well within the ten per cent limit set by regulators last year, a number of lenders have responded by cutting the rate premium they charge investors.The latest Reserve Bank lending figures show that lenders' investor mortgage balances grew by 8.5 per cent over the 12 months to December.According to comparison site Mozo, six lenders reduced the investor premium in January.AMP cut the variable rate on its Professional Pack by six basis points for owner-occupiers with loans up to A$750,00 and by two bps for owner-occupiers with loans over $750,000. It cut the rate by 38 bps for investors with loans up to $750,000 and by 40 bps for investors with loans over $750,000.Suncorp cut the variable rate on its Home package Plus Special by 15 bps for owner occupiers and introduced a special investor rate of 4.42 per cent (the previous best investor package rate was 40 bps higher).ME cut the variable rate on its Flexible Home Loan Member package by 30 bps for investors.IMB Bank cut the variable rate on its Essentials Home Loan by five bps for investors. The bank also cut fixed rate for investors.Newcastle Permanent increased fixed rates on one and two-year loans for owner-occupiers and reduced them for investors.