The South-East Regional assembly is to discuss a plan for a 40% target for affordable housing in all new-build developments.

The proposal will be debated at a meeting on Monday. If it is adopted, the South-east would be the first region outside London to set a region-wide target for affordable housing. It could mean that 288,000 affordable homes are built in the South-east if housebuilding targets of 36,000 homes a year for the next 20 years are approved.

The 40% target could include 25% for homes for social rent.

The assembly is set to begin consultation on three proposed levels of housing growth: the current ODPM targets of 29,500 a year; 32,000 a year; or 36,000 a year.

Ray Bowers, the assembly’s head of spatial planning, said: “Affordable housing is the big priority. There is a big gap between what most people can afford and average prices. We want the right to buy to be limited.”