The badger cull is expected to begin in the spring
A planned badger cull to tackle the spread of TB in cattle has been called "perverse" by an ex-senior scientific adviser to the UK government.
Dr Chris Cheeseman called on Welsh Assembly Government officials to reconsider the cull in Pembrokeshire, saying it could make bovine TB worse.
It is expected to start in the spring as part of a package of measures.
The assembly government said studies indicated a cull of badgers could have an impact on infection in cattle
But Dr Cheeseman said the decision "flies in the face of the science" and could make bovine TB worse.
The cull will take place over a five-year period, alongside tighter restrictions on cattle movements, improved testing regimes and better biosecurity to protect cattle from the disease.
Dr Cheeseman, retired head of wildlife diseases research at the Central Science Laboratory, told BBC Radio Wales' Eye on Wales programme that evidence indicated badgers would move out of the area and settle elsewhere, potentially taking the infection with them.
Altogether I think it's a perverse decision which, even at this late stage, should be rethought
Dr Chris Cheeseman, ex-scientific adviser to the government
"I think the decision to cull flies in the face of the science," he said.
"They've got to take account of the fact that it will raise the prevalence of TB in badgers, there will be a negative edge effect.
"The benefits - if there are any - are likely to be rather small, and they won't be able to tease out what the effects of culling are because they're including culling with cattle control measures so you can't separate those scientifically in the results.
"Altogether I think it's a perverse decision which, even at this late stage, should be rethought."
The cull area covers north Pembrokeshire, and a small part of Ceredigion and Carmarthenshire.
Christianne Glossop, chief vet to the assembly government, said studies indicated a cull of badgers could have an impact on infection in cattle.
"We have sought advice from experts in wildlife, we've spoken with veterinary surgeons and epidemiologists, and the policy we've developed has the support of the British Cattle Veterinary Association and the British Veterinary Association, and that's good enough for me," she said.
"There have been a number of studies through the years - in Ireland, in the south-west of England and particularly the randomised badger culling trial - which shows that if you cull badgers, that can have a direct impact on the incidence of infection in cattle.
"It's demonstrating quite clearly that there is a link between infection in cattle and infection in badgers."
The assembly government is facing a legal challenge over the cull from Badger Watch and Rescue Dyfed and the Badger Trust.
Fellow protest group, Pembrokeshire Against the Cull, said it was also seeking legal advice with a view to a possible challenge on the basis that the assembly government did not adequately consult landowners about the cull.
Eye on Wales is broadcast on Monday, 22 February at 1832 GMT, BBC Radio Wales.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.