A Labor-dominated committee report on Friday warned the relocation, due to finish in mid-2019, risked causing a five-year fall-out harming the quality of the Australian Pesticides and Veterinary Medicines Authority's work regulating agvet products.

Senators urged the federal government to consider the move's impact on staff capability and capacity, a recommendation rejected by the committee's Coalition members defending their parties' decentralisation policy in a dissenting report.

Labor and Greens senators said additional pressure on the pesticides authority created by its relocation from Canberra to Armidale, and the loss of experienced staff that followed, had exacerbated underlying problems causing delays in its work.

"The relocation has caused considerable disruption to staff and severely weakened the authority's ability to operate effectively and efficiently," the report said.

Nationals senator Barry O'Sullivan and Liberal senator Slade Brockman singled out the recommendation for criticism, saying the Coalition policy to decentralise Australian Public Service jobs from Canberra, Melbourne and Sydney would create employment in the regions.

"Decentralisation is also about equity. Rural and regional Australians deserve government careers just as much as city people. Regional economies deserve government agencies just as much as capital cities do," they said.

The Senate inquiry into the independence of the agricultural chemical regulator, triggered by Labor after questions raised over the agency's funding and corporate tactics of the company producing Roundup, cleared the pesticides authority over its regulation of the commonly-used herbicide. Greens senator Janet Rice, in another dissenting report,  recommended an independent review of the product's chemical risk.

Directing criticism at the agency's forced move to Armidale, a policy promised by the Coalition before the 2016 election and driven by member for New England Barnaby Joyce, senators said the relocation had delayed much-needed reforms aimed at speeding up approvals for new agvet chemicals and medicines.

The relocation had also brought into question the independence of the authority.

"The decision to relocate the APVMA to Armidale has hampered the regulator's ability to address a number of long-running issues with regard to its performance and funding," the committee said.

"Without any prior strategic planning to address the inevitable upheaval that would come from relocating a specialist scientific agency, the regulator has lost important institutional knowledge and technical expertise and must now overcome numerous challenges to effectively and efficiently carry out its functions.

"Evidence to the committee has suggested that it will take the APVMA a number of years to regain its lost scientific, technical and management strength."

The pesticides authority in its latest annual report said its rate of exiting staff increased in 2017-18 to 36 per cent, compared to 11.8 per cent in 2014-15 and 23.7 per cent in 2016-17. Agency chief executive Chris Parker in February last year said the majority of departing staff had likely resigned because they didn't want to move to Armidale.

Following calls to cancel the move north, Agriculture Minister David Littleproud vowed it would continue after he took Mr Joyce's portfolio last year. Dr Parker later revised the agency's relocation plans, deciding to keep 40 staff in Canberra after finding the shift to Armidale wouldn't work without the compromise.

The Coalition appears to have backed away from relocating public servants to the bush in other agencies, choosing instead to create new positions at regional offices in recent decentralisation announcements for the marine safety authority and Aboriginal Hostels Limited.

Despite the government's promotion of decentralisation, public service commission figures show inner-city centres on the east coast have amassed the greatest share of Australia's new federal jobs under the Coalition as outer suburbs, bush towns and Canberra took cuts to their ranks of bureaucrats.

A federal economic advisory body in 2017 dismissed decentralisation as a costly and ineffective way to grow regional wealth that risked damaging the performance of government agencies.