Mr Coe made the comments after a report on a 2007 Cabinet submission that showed the ACT government had been warned about the effects of its land supply monopoly on housing affordability repeatedly since 2001.

Former ACT Treasury official Dr Khalid Ahmed said the Stanhope government had tried to balance the need for land sales revenue with social and other objectives, though he believed that objectives had fallen by the wayside since.

Mr Coe said the report on the Cabinet submission had now confirmed the Labor government had knowingly used its monopoly on the release and development of land in Canberra to drive up revenue, in turn affecting the cost of housing.

He said when a buyer could only get a 350 square metre block of land in Gungahlin for $400,000, then had to finance the construction of a house, it was clear the system was not working.

While the Opposition has previously promised to cut rates and increase land supply for free-standing homes, Mr Coe also said he would look to speed up and simplify planning approvals in the territory if the Liberals won office in 2020.

He said he wanted to speed up development to ensure more homes could be built more quickly, though, with the construction industry already at capacity with existing projects both in the territory and NSW, it is unclear where additional workers could come from.

The Opposition has also pledged to abolish payroll tax alongside a potential capping of rates, and it unclear whether the party would cut spending or increase other revenue raisers to make up the more than $500 million shortfall.

For its part, the government has pledged to redevelop 1000 more public housing dwellings over the next five years, funded by more public land sales, and a range of mechanisms it hopes will increase affordability, though the detail has not yet been forthcoming.

But Mr Coe said given the Labor government in its various forms over the past 18 years, had known about the increasing effects of its monopoly on land release and development, it had failed to find basic solutions that could help cut the cost of living.

He also said he largely supported the government's push for major infill development along the light rail corridor and in the city, he wanted such higher-density projects in the town centres, to help preserve the 'suburban way of life'.

Mr Coe said while many people were happy to live in apartments, others wanted larger blocks with backyards at different stages of their life, and given there was no shortage of land, Canberrans should be able to access both at affordable prices.

A response to Mr Coe's claims was sought from the territory government on Friday.