Former chief minister Jon Stanhope has accused the ACT government of price gouging on land, as new analysis shows its profit margin on sales has risen dramatically in the past decade.
Mr Stanhope joked that only outlaw motorcycle gangs were reaping the same "supra profits" as the territory was from land sales.
Mr Stanhope savaged the Barr government's approach to planning and land supply during a seminar on housing affordability on Thursday.
He used analysis prepared by former ACT Treasury official Khalid Ahmed to push his claim that policies adopted by successive Labor governments had driven up land prices and made housing unaffordable for hundreds of thousands of Canberrans.
Analysis of Land Development Agency and Suburban Land Agency reports showed that almost 2000 fewer blocks were released to market last year than in 2010-11, despite strong population growth in that period.
As land supply reduced across the decade, profit margins from sales soared, according to the analysis.
In 2009-10, the Stanhope-led government extracted a 36 per cent profit margin from land sales. In 2017-18, the Barr government saw that margin increase to 84 per cent.
On Thursday, Mr Stanhope said as chief minister, he was "so appalled" at the 36 per cent profit margin that he "demanded that it be addressed immediately". The profit level dropped to 25 per cent the following year, which he said was consistent with industry standards.
It's about money. It's about money more than it is about meeting the housing needs of the people of Canberra.Former chief minister Jon Stanhope
"We didn't want to be a gouging government," he said.
After Mr Stanhope's departure in 2011, profit margins from land sales rose each year before reaching a peak in 2017-18.
"The only other industry in Canberra where the gross profit margin is around 84 per cent is outlaw motorcycle gangs," he said on Thursday.
"The banks aren't, the petrol companies aren't. I hear this language around the outrageous prices of petrol in the ACT, I bet the petrol companies aren't making a gross profit of 84 per cent.
"There is only one company in town that are making those levels of profit and it's those that sell the land - and we have a monopoly supplier in the ACT.
"It's about money. It's about money more than it is about meeting the housing needs of the people of Canberra."
In a statement late on Thursday, a government spokeswoman rejected claims that it had deliberately constrained land supply.
The spokeswoman said the the government had released land for 35,000 dwellings in the past nine years, including more than 10,000 single residential blocks.
She described land as a "scarce resource" and said the government had a responsibility to taxpayers to ensure "the public sees a benefit to it being sold for private use".
There were currently 600 blocks available to buy across the territory, she said.
"The government's land release program aims to make sure enough land is released to the market to cater for Canberra's growth and change," she said.
"It takes into consideration changes in population, changes in household and community needs and shifts in economic activity."
In its 2018-19 annual report, the Suburban Land Agency said that its profit margins were not comparable with the private sector. That was due, in part, to the fact that other government agencies paid for infrastructure in and around development sites, which were not reflected in the agency's financial results.
Mr Ahmed's analysis also showed the ACT government was becoming increasingly reliant on land sales to shore up its budget position.
Profit from land sales accounted for 11 per cent of the ACT's total "own source" revenue in 2017-18, up from four per cent in 2010-11.
"That is a dangerous trend," Mr Stanhope said.
"This has very, very significant implications because the government is on the teet for land sales."
The seminar was hosted by the Institute for Governance and Policy Analysis at the University of Canberra, where Mr Stanhope is a professorial fellow.
The ACT government's budget took a hit last financial year, after the Suburban Land Agency fell about $167 million short of its estimated income for 2018-19.
A sluggish housing market, tighter bank lending conditions and uncertainty leading in to the federal election all contributed to "well below average" rate of sales in the Canberra region, according to the agency's annual report.