TWENTY legislators and public estate tenants last night began a sit-in at the Housing Authority in a last attempt to press the authority to abolish the controversial double-rent policy. Authority members will discuss a review report on the five-year policy at a full meeting this morning. They will decide whether it should be cancelled or how it would continue. The policy requires families exceeding a certain income level to pay twice the normal rent. Sir David Akers-Jones will also chair for the last time the authority's open meeting as his resignation will take effect later this month. Angry public estate tenants swamped the authority's Ho Man Tin headquarters last night and burned copies of housing ordinances and documents of the double-rent policy. Protest organiser Ms Leung Yuk-fung, of the Hongkong People's Council on Public Housing Policy, threatened more violent protests if the authority did not abolish the policy. She also demanded that all members be removed if they ignored public opinion. The council also criticised the authority's move yesterday of lowering the discount on the latest batch of Home Ownership Scheme (HOS) flats. Spokeswoman Ms Virginia Ip Chiu-ping said the move would push up HOS flat prices. The authority reduced the discount by five percentage points in view of stabilised private property prices, it said. About 5,500 flats under six HOS projects will go on sale in the middle of next month, with a 40 per cent discount to market values. The discount at the last sale in December was 45 per cent. The acting chairman of the authority's home ownership committee, Mr Norman Leung Nai-pang, said applicants should find the flats affordable as the income limit was raised by 11.1 per cent earlier this month. Households with a monthly income of up to $20,000 - against $18,000 - are eligible for HOS flats. Mr Leung added the average prices of the flats would be about the same as those in the last sale. On sale will be 5,512 flats in Tsz Wan Shan, Stanley, Kwun Tong, Junk Bay, Fanling and Tuen Mun. Flat sizes are between 39.5 and 60 square metres, with prices ranging from $656,000 for a small flat in Fanling to $1.26 million for a big one in Tsz Wan Shan. Details of the sale will be announced next month. The Hongkong Home Ownership Scheme Council also expressed fears that lower-income groups could be driven out of the HOS flat market given the lower discount. Chairman Mr Li Man-kwong said: ''Prices of HOS flats in Fanling have risen by more than 10 per cent when compared with the last sale. I do not see how buyers can afford with a lowered discount this time.''