Flats in the mass market have become much less affordable in the past six months. The mortgage repayment to income ratio has increased from about 30 per cent last year to more than 45 per cent this month, Monetary Authority statistics show.
For luxury flats of more than 100 square metres meanwhile, the ratio surged from just over 50 per cent last year to more than 70 per cent this month.
The authority defines flats in the mass market as those with an area of less than 100 square metres.
In a presentation to the Legislative Council, the authority also warned that an increase of three percentage points in the interest rate would push repayments up by about 30 per cent.
Financial Secretary John Tsang Chun-wah appealed to people in a speech last month to carefully assess the impact of future interest rate rises on their ability to repay their mortgages. At that time, the government-calculated repayment ratio - based on a flat of 45 square metres - was 42 per cent, up from 38 per cent in the last quarter of 2009.
New flat sales measures and land auctions have been announced by the government over the past three months to reduce speculation and increase land supply.