Taxpayers will be billed $25.6 million to cover the cost of relocating a chemical regulator from Canberra to Armidale, in the Deputy Prime Minister Barnaby Joyce's electorate.

Key points: Authority to be located at least 150 kilometres away from Canberra

Authority to be located at least 150 kilometres away from Canberra Farmers, veterinarians and chemical manufacturers oppose the move

Farmers, veterinarians and chemical manufacturers oppose the move Cost benefit analysis is also expected to be released today

Mr Joyce, whose office has confirmed the move, has been pushing to relocate the Australian Pesticides and Veterinary Medicines Authority (APVMA) to Armidale since June.

But farmers, veterinarians and chemical manufacturers oppose the move, fearing the Authority will lose highly specialised experts from its staff.

Today an official policy order issued by the Federal Government will come into effect, requiring the authority to be located at least 150 kilometres away from Canberra.

The order cannot be disallowed by Parliament.

The Government's own cost-benefit analysis, worth $272,000 and conducted by Ernst and Young, found there were no material economic advantages to support the relocation.

The report warned the APVMA may be unable to relocate, recruit and replace key technical staff and management, and could lose access to stakeholders.

The report warned chemical companies may leave the Australian market and lose up to $2.37 million in revenue due to short-term productivity damages.

Just 15 per cent of the APVMA workforce are prepared to relocate to Armidale and the report considered significant staff losses as "highly likely".

Mr Joyce has faced stinging criticism from the Opposition for the plan to move the APVMA.

He previously claimed that moving the body to Armidale would contribute about $16 million a year to the local economy, and create an additional 175 jobs.

He announced the decision in June, ahead of the federal election in July, and said the relocation of the registration authority to Armidale would create an agricultural centre of excellence in his electorate of New England.

Extreme case of pork-barrelling, Labor senator says

But Labor accused Mr Joyce of "pork-barrelling" and announcing the relocation without waiting for the green light from the Prime Minister.

"We've got hundreds of families being told 'move to Armidale of lose your job' because Barnaby Joyce has decided that he wants this agency in his home town," ACT Labor senator Katy Gallagher said.

"And if a minister, despite what everyone is saying, writes a new rule saying 'this agency can not be established within 150 kilometres of Canberra', that leads to the question of 'what next?'

"This place was established as the seat of government, where government business should be conducted and we've got an out-of-control Deputy Prime Minister deciding that he can move things around with the stroke of his pen."

APVMA could lose up to 85 per cent of its Canberra workforce. ( ABC News: Ian Cutmore )

The APVMA relocation is part of Mr Joyce's broader plan to relocate parts of several government departments, including the Rural Industries Research and Development Corporation to Wagga Wagga and the Grains Research and Development Corporation to Toowoomba.

He sees it as a way to boost regional economics and put researchers closer to rural industries, but the Opposition has argued the relocation will cost the Authority millions of dollars including a breach of contract on tenancy and redundancies.

National Farmers' Federation members voted against the relocation last year.

Labor's shadow minister for agriculture, Joel Fitzgibbon, said the relocation would undermine the APVMA's capacity to ensure farmers could access chemical and animal medicines.

"It is now clear to all those in rural and regional Australia that Barnaby Joyce will always put his own political interest ahead of the interests of our farmers," he said.

David Smith, director of the staff association Professionals Australia, said if some experts could not move to Armidale they may have trouble obtaining another job, due to their targeted skills.

"They're particular experts, so they're not necessarily going to be able to use their expertise in a field that still needs it," Mr Smith said.

"Leading into Christmas, this isn't great news."