MELBOURNE is headed the way of Los Angeles, with sprawling suburbs and growing traffic woes because of strong population growth and poor planning, experts and developers have warned.

Federal Treasury has estimated that in the next 40 years Melbourne's population will increase by up to 75 per cent, to almost 7 million residents.

Based on the State Government's latest growth projections and land requirements, Melbourne would need to build 1.8 million dwellings to meet the population demand, and its urban boundary would need to expand by 123,000 hectares. Half of the new homes would be in growth areas.

''Melbourne cannot survive this kind of sprawl - we are going to end up the way American cities are going. It is a horrendous future and the Government has got to stop it happening,'' RMIT University associate professor Michael Buxton said.

''If you look at a city like London, it has a boundary that has been fundamentally unchanged now for over 60 years and they just keep finding vast amounts of land within the metropolitan area,'' he said.