A Coalition plan to fast-track 300,000 housing lots in outer growth suburbs has been described as a “recipe for long-term disaster” by one senior planning expert.

Opposition leader Matthew Guy has pledged to fast-track the rezoning of all Precinct Structure Plans – about 300,000 extra housing lots – in Melton, Wyndham, Hume, Whittlesea, Mitchell, Casey and Cardinia, by 30 June 2020.

Mr Guy said increasing land supply will drive down demand, thus making more houses affordable. But planning expert and RMIT University Emeritus professor Michael Buxton said increasing land supply in outer growth areas was “the most unsatisfactory solution” to tackling housing affordability.

He said the proposal did not address one of the most pressing issue of growth boundaries – poor infrastructure and services.

“Governments internationally manage to deliver affordable housing types right across the city and metropolitan area, and that takes planning, economic policies, employment policies,” professor Buxton said.

“In a way … a quarter of a million new households on the fringe is giving up on the fundamental task, which is to provide a range of affordable housing [across Melbourne].”

He said focusing on land supply will only create other problems, including adding further strain on overstretched areas.

Planning, which involves varying housing types and land sizes, will be a much better solution to addressing the housing affordability crisis, Professor Buxton said.

“Government should get away from trying to outbid from providing the worst housing options in the fringe suburbs,” Professor Buxton said. “This is a bidding war to the race of the bottom to provide bad housing.

“Putting another 250,000 on the fringe is a recipe for long-term disaster.”

Melton mayor Bob Turner said the council wasn’t officially made aware of Mr Guy’s plans, but said it was struggling to cope with its current population boom and was playing catch up from past planning failures.

He said while housing affordability was a problem, releasing thousands of new lots without infrastructure wasn’t the solution.