A group of vets has accused Defra of telling "barefaced lies" about the progress of the badger cull in England.
Prion Interest Group has written to the UK's Chief Vet, Dr Christine Middlemiss, asking her to ensure Defra retracts "insupportable claims that its badger cull policy is working".
Defra Farming Minister George Eustice announced reductions in new outbreaks of bovine TB were recorded in Gloucestershire and Somerset following the completion of their licensed four-year badger culls.
The data, published on 13 September, showed a decline in TB incidence in the first two cull areas with the rate of new confirmed breakdowns now at about half the level they were before culling began.
In the Gloucestershire cull area, the data showed TB incidence fell from 10.4% before culling started to 5.6% in year four of the cull, while in Somerset it has reduced from 24% to 12%.
But Dr Iain McGill, a veterinary surgeon and director of Prion Interest Group, told BBC News that Defra's claims that badger culling lowered bovine TB cases in cull zones amounts to "barefaced lies".
"According to Defra's figures, they claim that they calculated that the incidence [of TB in cattle] has reduced," Dr McGill said.
"But their calculations are unclear and deliberately opaque. And, indeed, the current situation in the cull zone says there is an increased prevalence."
He added: "So, either their figures were calculated on an extremely inaccurate basis and they've got it very badly wrong, or they have actually gerrymandered those figures to make it look as if the incidence is falling when the evidence clearly shows that the prevalence has gone up.
"Badger culling has not worked. They are issuing barefaced lies in this matter."
However, a Defra spokesman said all statements had been "absolutely correct".
It follows an open letter released in October, published in The Observer from veterinary and animal welfare figures, calling on Mr Eustice to retract the statement he made in September about the badger cull progress.
The open letter requested that Defra release the data upon which their calculations for incidence and prevalence are based.
England has the highest incidence of bovine TB in Europe and the disease costs taxpayers over £100m every year.
In 2017 more than 33,000 cattle had to be slaughtered in England to control the disease.
