The National Capital Authority is assessing developer Amalgamated Property Group's application to demolish the derelict office building at Anzac Park East, at the north-eastern corner of Anzac Parade and Parkes Way.

The developer also plans to rip up the rear carpark and axe the site's trees, according to application documents.

The works would pave the way for a transformation of the Commonwealth heritage-listed site, which has been vacant for more than 20 years.

In an application to the authority prepared on behalf of the developer, consultants Canberra Town Planning said the future development would include a "mix of commercial and residential uses, with commercial uses to face Constitution Avenue".

The application does not provide further details on the proposed development, but said it would align with the National Capital Plan's vision for a "vibrant mixed-use grand boulevard linking London Circuit to Russell".

A National Capital Authority spokeswoman said buildings of about 35 meters in height were permitted on the site, which could be used for housing, hotels, offices and shops.

The existing building is 25 metres, or six storeys, tall.

Amalgamated Property Group did not return calls from The Canberra Times, but the developer has previously flagged the possibility of transforming Anzac Park East with a mix of housing, offices, shops and restaurants.

The office block has sat idle since its last government tenants vacated the site in 1997, making it a target for vandals and an eyesore for passers-by.

In 2014, The Canberra Times reported that in the previous five years the federal government had spent $1.6 million maintaining the 12,500 square metre building, which was later found to be contaminated with mould and asbestos.

The federal Finance Department last year sold the land for $34.3 million as part of a wider sell-off of ageing government buildings in Canberra's parliamentary triangle.

The scheme, which yielded the government a total of $122.5 million, marked the first private ownership of land inside the historic precinct.

Amalgamated Property Group, headed by well-known local developer Graham Potts, also snapped up land on Constitution Avenue for $21.7 million during the sale.

Anzac Park West was also sold to EG Funds Management Pty Ltd for $51 million as part of the divestment program.

The sale and future redevelopment of Anzac Park East and West sparked alarm when it was first confirmed in December 2016, with heritage advocates fearing the vista from Parliament House to the Australian War Memorial could be "spoilt" unless the so-called portal buildings were rebuilt simultaneously, and in symmetry.

The twin buildings, designed by National Capital Development Commission architect Gareth Roberts, were built in 1965 and 1966. They are the only Commonwealth Heritage-listed buildings on Anzac Parade, aside from the Australian War Memorial.

While Anzac Park East must be redeveloped within four years under the terms of the sale contract, the west building could remain standing for the next 30 years because of a long-term lease with the Defence Department.

The Walter Burley Griffin Society's Canberra chapter chair, Brett Odgers, was concerned the new development would not be "sympathetic" to Griffin's vision for the location.

"The two existing buildings serve an important purpose, and NCDC designed them that way, so we would be very worried if it detracted from that," Mr Odgers said.

"The new buildings that are being built [in Canberra] are not setting any great architectural standards."