The Avon Green Belt, also known as the Bristol and Bath Green Belt (or Bath and Bristol Green Belt), is a non-statutory green belt environmental and planning policy that regulates urban expansion and development in the countryside surrounding the cities of Bristol and Bath in the South West region of England. It covers areas in Bristol, South Gloucestershire, North Somerset, Bath and North East Somerset, Mendip, and Wiltshire. Essentially, the function of the green belt is to limit urban sprawl and maintain the open character of areas around the Bristol and Bath built up areas, and nearby towns and villages. The policy is implemented by local planning authorities on the basis of guidance from central government.