Chase Manhattan Bank said an expected 25 basis-point rise in United States interest rates would reduce pressure on banks to lift mortgage rates further. Head of consumer loan business Alan Tsang Hing-lun said mortgage rates had been reduced significantly since January due to intense competition. 'The dramatic surge in property prices during the same period has increased the risks in home loans, making low mortgage rates unsustainable,' he said. The mortgage rate rises began last month when Hongkong Bank revised its minimum rate to 9.25 per cent. Mr Tsang said any rise in the US would widen the interest rate differential.