Gai Brodtmann says the controversial move of the pesticides authority to the heart of Deputy Prime Minister Barnaby Joyce's electorate in northern NSW "ignorantly disregards" the wishes of Mr Menzies for the future of the capital.

A parliamentary committee is investigating the process that led to Mr Joyce ordering the Australian Pesticides and Veterinary Medicines Authority to Armidale, despite almost universal opposition to the move.

The controversy flared up again this month when the agency's boss revealed that she and other senior staff were spending their days in a McDonalds restaurant in the town, doing their work using the burger joint's free wi-fi because there was no other office space for them in Armidale.

In her submission to the Senate's Finance and Public Administration References Committee, Ms Brodtmann acknowledged Mr Menzies was not always enthusiastic about Canberra, but came to regard the city as "an object of pride and pleasure"

"Sir Robert Menzies would be turning in his grave" over Mr Joyce's "decentralisation" ambitions.

"The Turnbull government is doing its level best to destroy the legacy of the founder of the modern Liberal Party," Ms Brodtmann wrote.

"The Turnbull government's cabinet decisions and subsequent order to relocate the APVMA from Canberra to Armidale ignorantly disregards and misunderstands the purpose of Canberra and unpicks Sir Robert Menzies' vision to establish a Commonwealth seat of government and administration in one location - the nation's capital."

Mr Joyce, whose office was contacted for comment on Monday, has argued that moving agencies out of Canberra and to the regions is a way for the government's "largesse to be more evenly spread around the country".

He and his National Party colleagues have called on regional councils to use the inquiry, which was forced on the government by Labor and Greens, to make their pitch for Canberra public service outfits to be moved to their towns.

But Ms Brodtmann, in her submission, says the idea is contrary to whole notion of having a national capital.

"It is nothing more than a blatant, political and shameless act exercise in pork barrelling to shore up support for Nationals in regional seats premised on the spurious notion that Commonwealth government needs to be decentralised," the Canberra MP wrote.

"Already more than 60 per cent of Commonwealth government work is conducted outside of Canberra, the majority of which is provided by service delivery agencies such as Centrelink or Veterans Affairs.

"The APVMA is not a service delivery agency, it is a regulatory authority."

Elsewhere in her submission Ms Brodtmann takes aim at the costs of moving the APVMA to Armidale.

"The Turnbull government's own $272,000 independent cost-benefit analysis shows the relocation is all cost and no benefit," she wrote.

"The analysis shows the relocation will cost $23 million, at a minimum, excluding as it does 'any potential cost to industry arising from the risks to the agricultural sector, the chemical industry or Australia's trading reputation'."