Three senior scientists who collectively produced two decades of government research on controlling badgers to reduce bovine TB are among a group of eminent experts to call for an immediate halt to the badger cull. The intervention comes as figures reveal the government has spent nearly £7,000 killing each badger so far.

Professor Lord Krebs, Professor John Bourne and Professor Ranald Munro write of their disappointment that the Department for Environment, Food and Rural Affairs (Defra) has extended the controversial cull to Dorset and called on it to immediately reconsider its decision to continue culling badgers.

It is the first time that Munro has publicly criticised the government after he was employed by Defra in 2013 to chair its independent expert panel on the badger cull. The panel concluded that the first year of the pilot culls in Somerset and Gloucestershire failed to meet Defra’s own criteria for effectiveness or humaneness.

Badger cull is flawed and must now stop | Letter from Ranald Munro, John Bourne and others Read more

Defra ignored these findings, scrapped the panel and continued the badger cull last year and this year. As the experts’ letter states: “No improvements to humaneness were reported following the second year of culling, leading to the withdrawal of the British Veterinary Association’s support for the method.”

Lord Krebs of Oxford University was originally commissioned by the government to investigate links between badgers and the spread of bovine TB in cattle and his influential report in 1997 led to an eight-year £50m government-funded field trial, in which the impact of culling 10,979 badgers was scientifically monitored in the countryside.

That trial, led by Bourne, concluded in 2007 that culling badgers could “make no meaningful contribution to cattle TB control in Britain”. The experiment showed how culling could make bovine TB worse if it caused the “perturbation effect” whereby killing badgers caused survivors to roam more widely, spreading the disease into new areas.

Despite this, pilot culls were launched by the government in areas of Somerset and Gloucestershire using “controlled shooting” – a method of killing badgers not tested by the rigorous scientific trial, which trapped badgers in cages before shooting them, to minimise suffering and perturbation.

In the letter, the experts stress the “considerable” evidence demonstrating “the central importance of cattle-to-cattle transmission” in the spread of bovine TB.

They write: “Control strategies require wider recognition of other factors, including the limitations of the tuberculin test [which determines whether cattle have bovine TB], more rigid cattle movement controls and heightened on-farm biosecurity. These measures are far more effective at reducing tuberculosis in cattle. Vaccination of both cattle and badgers may also have a role to play.”

In further criticism of the government, Bourne accused Defra of continuing “to either ignore, cherry pick or purposefully misinterpret the science” on badger culling.

He said that while cattle control measures had been strengthened they were still inadequate. “Defra fail to fully appreciate that this is primarily an infectious disease of cattle and that the tuberculin test is very insensitive. As a consequence large numbers of infected cattle remain undiagnosed and perpetuate the disease in infected herds as well as spreading the disease to other cattle herds and wildlife.”

Another signatory of the letter, Professor Alastair MacMillan, veterinary advisor to Humane Society International, said: “Experts agree and the verdict is in: a cull of up to 2,038 badgers in the coming weeks would be inhumane, ineffective and indefensible. It’s long overdue that the government listens to science and reason and ends the badger cull.”

Separately on Wednesday, the Badger Trust published figures released by Defra under a freedom of information request showing that the government had spent £16.8m on the badger culls since 2012, or £6,775 per badger killed.