THE Housing Authority has recovered 73,400 public housing flats since the Home Ownership Scheme (HOS) was introduced in 1978, the Government revealed yesterday. Acting Secretary for Planning, Environment and Land, Mak Chun-fong, said all the 73,400 tenants who succeeded in getting HOS flats had surrendered their rental units soon afterwards. Under existing regulations, tenants have to move out of their public housing flats within two months of taking over HOS flats. Only under special circumstances could they be granted a longer period in which to move, he said. Mr Mak said there were no reports of any tenants keeping their public housing flats after they had taken over their own flats. 'Neither the Government nor the Housing Authority is aware of any tenants living in HOS flats for years without surrendering their public rental flats,' he said. The Housing Authority has tried to encourage more public housing tenants to buy HOS flats by setting aside two thirds of the HOS flats for applications by tenants, said Mr Mak. 'More public housing flats will thus be made available for those in need,' he said. So far, 37 per cent of the 200,800 HOS flats have gone to public housing tenants.