"So what's being promised is being reduced and even that reduced target isn't being delivered," he said, pointing to the need for strong political commitment to drive land release.

Dr Ahmed, who was on the Council of Australian Government's housing affordability working party and now works in the private sector, will speak at a public seminar organised by former chief minister Jon Stanhope on Thursday, where economist Ben Phillips will also speak.

Mr Stanhope said he was concerned about the enormous stress faced by young families trying to find a home and make mortgage payments, and he had also talked to builders concerned about land prices and the lack of land for sale.

"Some young families that I've spoken to over the last three months have told me that they've purchased three-bedroom government houses in Canberra for in excess of $500,000, and that's now almost at the bottom end of the market in relation to houses," Mr Stanhope said.

For many, all they could afford was a unit, and they were "irritated by the fact that affordable new housing in Canberra today is defined as a unit".

Mr Stanhope said he remained mystified about what had happened with an affordable housing action plan developed when he was chief minister, which had recommended a year's supply of land always be development-ready. It had never happened, despite being government policy, he said. The Land Development Agency has no single housing blocks for sale at the moment.

Dr Ahmed said while soaring house prices were a complex problem, land availability was at the core. In Canberra, that was easy to fix, given the government owned all the land, plus had control of planning.

"Affordability shouldn't be as big a problem as it is in Canberra because we have absolute control over the land supply," he said. "If you have got the policy settings right, the rest will take care of itself. If you supply enough the prices will stabilise."

In Canberra, median house prices were five times median incomes, and had been stuck there for about a decade (nationally, the average is 6.8). In 1990, prices were three times incomes.

Dr Ahmed said the true scale of the problem was worse than those figures suggested, with people on moderate incomes in a worse position. For them, standalone homes were no longer an option. When first-home buyers could not buy established homes, but were forced to new estates and apartments, it was a tell-tale sign of problems throughout the market, he said.

The problem had taken off in the early 2000s, when house prices rose 60 per cent over 18 months, with the goods and services tax, the first home owners' grant and easy credit.

While prices rose fast, they were more "sticky" on the way down – especially in Canberra, where affluence at the higher end of the market helped keep prices high and keep the market active, and disguised the struggle among people on moderate incomes.

Dr Ahmed said he did not see the market being geared up to deal with a surge in demand and feared things would get worse.

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A decade of greater land release was needed to bring prices under control.