Plans to cull badgers as part of the fight against tuberculosis in cattle have been criticised by a senior government adviser on the disease.
Farmers argue badgers should be gassed, not shot
Professor John Bourne said a cull could worsen England's bovine TB situation, adding ministers had underestimated the level of culling required.
Conservationists say cattle movements are to blame for spreading the disease.
Most farmers say a cull is needed but disagree with government proposals, saying they do not go far enough.
A consultation was launched after ministers said TB was at crisis point.
More than £90m was spent on battling bovine TB last year but the debate still rages over how to tackle the disease.
Prof Bourne has now made public his doubts over cull proposals on BBC Radio 4's Farming Today programme.
He said: "There does need to be a far more aggressive focus on the cattle problem before one is going to see any decrease in the instance of the disease.
"There's no doubt in my mind that this would be achievable if there was concerted effort between farmers and government to more aggressively control the disease in cattle."
Anthony Gibson, who heads the Nation Farmers' Union in south-west England, also said government plans could make the situation worse.
He said farmers would refuse to take responsibility for snaring and shooting the animals, saying government scientists should gas them.
"We are keen on culling providing it is effective culling - to be effective it has got to involve the gassing of infected sets.
"We're not going to go along with partial control that could make the situation worse."
He claimed the government would not authorise the use of gas on badgers for at least another year.
But animal groups deny the necessity of culling the animals at all.
Dr Arthur Lindley, of the RSPCA, said scientific evidence showed a cull of badgers was "inappropriate".
"It certainly won't make the situation better, may well make the situation worse, and will involve enormous suffering."
He called for tighter controls on the movement of cattle and better testing of the animals.
The Department of Environment, Food and Rural Affairs (Defra) said it would welcome all opinions as part of its consultation.
Badger culling was just one of the proposals put forward by the government when it launched the consultation in December.