Farmers have threatened legal action if the Government decides not to allow a cull of badgers to tackle tuberculosis in cattle.
The president of the National Farmers' Union, Peter Kendall, said reports that Hilary Benn, the Environment Secretary, was not going to authorise a cull would be "nothing short of a disaster", if true.
Mr Kendall said a failure to cull badgers, which can infect cattle with TB, would have a devastating impact on farmers and rural communities in areas ravaged by the disease.
And Ian Potter, a farmer and industry commentator, from Ashbourne, Derby-shire, warned of demonstrations and the possibility of farmers taking the law into their own hands to deal with badgers. But conservation groups said that the reported decision was based on sound science.
With climbing rates of infection and 28,000 TB-infected cattle slaughtered last year, the Government has been under pressure to allow a cull in badgers, which farmers say act as a "wildlife reservoir" transmitting the disease.
Mr Benn, at the Royal Show in Warwickshire yesterday, refused to disclose what his announcement, expected on Monday, would be. But he acknowledged the scale of the problem.
Mr Kendall said: "Last year saw 28,000 cattle culled with TB, and already in the first quarter of 2008 another 13,500 cattle have been lost. This needless waste of productive animals is unacceptable and calls into question the Government's attitude to food security and animal welfare."
But conservation groups such as the Badger Trust, the Wildlife Trusts and the RSPB welcomed suggestions that there would be no slaughter, and insisted such a decision was backed up by the science.
A 10-year study by the independent group on bovine TB concluded last year that a cull of badgers could not "meaningfully contribute" to controlling the disease. But a review of the research by the former government chief scientific adviser Sir David King said a cull could make a significant contribution to bovine TB in areas where there was a "high and persistent" incidence of the disease.
Trevor Lawson, from the Badger Trust, said attention must be focused on cattle, "the main agents of the disease", with more frequent and better testing to identify TB and swifter action to remove infected animals from farms.