City Services Minister Chris Steel told memorial director Brendan Nelson he was "supportive" of the proposal to build a temporary car park and compound for builders at the popular gateway to Mount Ainslie.

Mr Steel told Dr Nelson in a May letter, released under freedom of information laws, the ACT government was open to giving the memorial a licence to use the park for a temporary car park and compound.

The ACT government had asked for more analysis of the environmental impact of the proposed construction buildings on the park, Mr Steel said.

Early signs from the territory government about the memorial's plans for permanent parking spots at the nature park were also positive.

Mr Steel said he could offer in-principle support if it was "an acceptable planning outcome" and the impact of hosting the construction buildings was found to be "acceptable".

The minister wrote in response to a February 25 letter from Dr Nelson, sent five days after the memorial director told a Senate estimates hearing of plans to use the nature park.

Dr Nelson, seeking Mr Steel's support for a permanent car park at the site, said people walking up Mount Ainslie would also use it.

The memorial had raised the proposal with Mr Steel's directorate, he said.

"There was general agreement that additional parking in this location would be a beneficial outcome for the ACT," Dr Nelson said.

Internal ACT government documents also reveal it was waiting in late April for a more detailed proposal from the war memorial for Remembrance Nature Park. The delay had caused "assessment difficulties" and ACT officials did not know the size of the planned compound, the minutes said.

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The memorial's plans for Remembrance Nature Park met swift resistance from advocates for the area in March. The park opened to commemorate the 60th anniversary of armistice, and to symbolise the peace and freedom Australians had defended.

When asked about plans to use the nature park for temporary buildings and a permanent car park, the war memorial last week said all early works would "currently" be within its own site.

The ACT government, which owns the land at Remembrance Nature Park, is yet to licence the war memorial to build there.

The territory hasn't received the assessment of the plan's environmental impact foreshadowed by Mr Steel.

Minutes from a March meeting of ACT officials noted the park had national- and territory-listed endangered species.

The memorial opened plans for its early expansion works to consultation with Campbell and Reid residents last week, when it discussed proposed extensions to its underground car park.

Dr Nelson said the car park extension would be the first stage of early works, starting in October, for the institution's major expansion project.

The war memorial also plans to build temporary on-site parking at the rear of Poppy's Cafe for builders and contractors.