A plan to offer more housing benefits to tenants on public estates was 'planting the seeds of social unrest', housing watchdogs warned yesterday. The Housing Bureau proposal reverses the current policy of avoiding 'double benefits' and seeks to allow public tenants to buy sandwich-class flats. The bureau said it wanted to offer public tenants more choices to encourage them to leave subsidised rental units to those most in need. The subsidy for a public tenant is about $350 a month. However, veteran housing affairs observer Ho Hei-wah, director of the Society for Community Organisations, attacked the move as being against the principle of fairness and of breaching the thinking behind the sandwich-class scheme. The sandwich-class housing scheme is designed to help middle-income families renting private homes to buy their own flats. It excluded public tenants because they are already entitled to many other Government housing schemes. A spokesman for the Hong Kong People's Council on Public Housing Policy accused the Government of risking social unrest. 'The proposed policy changes would set a very bad precedent. People would think that public tenants always get the biggest slice of the cake,' he said. Last month, the Housing Authority lifted a ban on public tenants buying so-called 'second-hand' home ownership units, sparking a debate on 'over-subsidising'. Details of the new policy changes are expected to be announced by year-end. The Housing Society, which is appointed to manage the sandwich-class scheme, said the new policy, if endorsed, would apply to 2,300 units due to go on sale early next year.