St Albans City & District Council's current local plan dates back to 1994 and the authority halted work on a draft local plan in 2012 so an independent green belt boundary review could be carried out.
Last month, the council began a six-week consultation on a draft strategic local plan, which contains proposals to release land from the green belt to meet housing needs.
More than 81 per cent of the district lies in the green belt, according to the draft plan. It identifies four areas of green belt for development - two east of Hemel Hempstead, one east of St Albans, and one north-west of Harpenden - that it estimates could accommodate around 4,500 homes.
The document explains that the council has taken specific legal advice on whether "exceptional circumstances" exist to justify a change to green belt boundaries.
It adds that the council has not yet made up its mind whether or not such exceptional circumstances exist, and will do so only after it has considered consultation responses. The draft plan outlines a scenario in which it is accepted that such circumstances exist, it says.
Council leader Julian Daly said: "If we get it right, the strategic local plan will help us protect the district from overdevelopment for the next two decades."
He added: "This is an open process, as councillors have not yet firmed up their views."