The National Capital Authority has begun its process of public consultation over controversial plans to overhaul the national institution.

The consultation will be run in three phases over a six-week period until September 10.

The first step, which is open until August 10, highlights the plans for three main projects, including artist impressions.

A new Anzac Hall design is featured along with an extension to the Bean Building and a new weatherproof main entrance connecting to the lower levels.

Three information sessions, allowing the public to chat to the architects behind the vision, will be held in mid-August.

Public submissions will open between August 21 and September 10 and will be published on the capital authority's site with permission.

It will mark the second public consultation period handled by the authority in recent months over the war memorial redevelopment.

Long-time opponents of the proposal, interest group Heritage Guardians, expressed their disappointment following the National Capital Authority's seal of approval back in June.

An overwhelming majority of the project's 600 submissions were highly critical of the proposed expansion's early works with only a handful supporting the plans.

Convener David Stephens argued the plan was never meant for the Australian people.

"This is a terribly disappointing outcome, not just for the many people who have argued strongly against the project but also for people who value Canberra as the national capital," Mr Stephens said in June.

"The redevelopment has been conceived in backrooms, has avoided normal accountability processes, and has been justified by the memorial's dodgy surveys of public opinion.

"Canberra - and Australia - deserved better than this."

A spokesperson for the NCA said there had been a misunderstanding of the authority's role in the approval process, noting it had already been approved in Parliament.

"Many people who made submissions objected the allocation of funding to this project and what the development proposes to achieve," an NCA spokesperson said.

"They may feel disappointed that they were not able to change the decision to move forward with the development, however, the funding of a project is not something that the NCA considers when making a planning assessment,"

For the second consultation period, the National Capital Authority would work to dispel some of these misunderstandings, the spokesperson said.

"The NCA is committed to community engagement and confirms it will continue to provide a public consultation process for all works applications it receives in accordance with the NCA's Commitment to Community Engagement policy," the spokesperson said.

"We take all of our consultations seriously. We want to hear the community's views on the design and materiality of the proposed works and suggested improvements to the overall propositions.

"The NCA will use the live streamed and public information sessions to clarify what the NCA can and cannot consider in this works application consultation process."

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Early works were approved this year and began in June with the removal of a number of trees along Treloar Crescent.

Construction workers and heavy machinery soon rolled in early July to undertake the task of pulling down the 20-year-old Anzac Hall.

It's expected the hall's demolition will be completed by mid-September.

The changes form part of a 10-year plan to expand the Australian War Memorial, which is expected to cost half a billion in total and expand exhibition space to include more recent engagements in Syria and Afghanistan.

Early works plans also include an extension to the underground car park and excavations to prepare for a new southern entrance.