Chief Executive Tung Chee-hwa's goal to build 85,000 flats a year could be foiled by the financial crisis, leading property developers warned yesterday. They called for a flexible mechanism to adjust the supply of flats in line with market forces, saying the turmoil had brought structural changes to the economy. The developers met top housing officials and academics to debate government plans to build 85,000 flats a year - including 50,000 public flats - at a Chinese University forum yesterday. Sung Hung Kai Properties vice-chairman Thomas Kwok Ping-kwong said the economic crisis had cast doubt on Hong Kong's ability to maintain five per cent gross domestic product growth over the next five years. 'If our economy weakens, the total demand for the 85,000 units will also be weakened . . . but it will be difficult to slow down the supply of 50,000 public housing flats a year once the government programme is fixed,' he said. 'The pressure to regulate in line with market demand will rest on the private sector. The Government must think of a flexible mechanism to avoid the supply of flats in the private sector fluctuating too much.' If the property market became too volatile, it would increase investment risks and have an impact on the economy, unemployment and competitiveness, he said. Cheung Kong (Holdings) representative Lee Yin-yui agreed there could be risks in an immovable 85,000-unit target, which would force private developers to find ways to survive. Professor Ho Lok-sang from Lingnan College said increased ownership of public housing could result in a chain reaction on the private sector, reducing the number of potential buyers. But Housing Authority chairman Rosanna Wong Yick-ming said the 85,000 annual target was a long-term goal that was needed because demand for public housing remained high. The aim was to have 70 per cent of the population living in their own homes by 2007, she said. Principal assistant secretary for housing Wong Chiu-ying said 50,000 public housing units were needed to meet demand from those who could not afford private sector flats. Housing demand would be reviewed twice a year, she said.