About 700 flat owners from eight sandwich-class housing estates yesterday urged the Housing Society to cut the interest rate on its mortgages to relieve their financial burden. Civil servant Yuen Man-chung said he bought a flat in Tinacle Garden, Tseung Kwan O, in 1997 for $2.5 million. He paid a 10 per cent deposit, borrowed $510,000 from the Housing Society and $1.74 million from banks. 'The current market price of my flat is only about $1.2 million and I will have to repay the society loan from 2004,' he said, adding that the total amount of mortgage repayment would soar to about $15,000 by 2007. 'My wife was sacked in February and it will be extremely difficult for us to bear the burden,' he said. According to a survey conducted by the Coalition of Sandwich Class Housing, 30 per cent of 1,500 flat owners spent 60 per cent of their monthly family income on mortgage repayments. Sixty per cent of respondents said their family income had dropped in the past three years, while 20 per cent said family members had been laid off. The survey was carried out at the end of last month. The coalition urged the Housing Society to cut its interest rate to 2.5 per cent, which is below the prime rate. Coalition spokesman Lai Yan-biu criticised the society for selling off its mortgages to the Hong Kong Mortgage Corporation without prior notice to flat owners. 'It will be difficult for us to get the interest rate cut after that deal,' Mr Lai said. 'The society is shirking its responsibilities towards flat owners.' He said the society should allow owners to start repaying its mortgage after 10 years rather than after five. The Housing Society said last night the owners had not been disadvantaged after their mortgages were sold to the corporation. A spokesman said the sale was a normal business deal and the corporation could better manage the mortgages.