Revealed: the needless slaughter of 2m animals

Top Government adviser speaks out on cull: 'Common sense totally suspended' : Ministers alerted to wrong policy in March

Ministers ordered the slaughter of up to two million healthy animals despite being told by their leading foot and mouth expert that the killing was not needed to control the disease.

They went ahead with the cull on uninfected farms near outbreaks even though they were told by a leading scientist at the Institute of Animal Health that the scientific basis for it was "a total suspension of common sense".

Officials now admit that some of the assumptions that led to the cull may have been wrong. But at the time, says Dr Paul Kitching – then head of foot and mouth at the institute's Pirbright Laboratory, the world's leading centre for research on the disease – his objections were ignored.

His revelations are bound to reignite the row over the scale of the slaughter. Nick Brown, the then Agriculture Minister, insisted that his "every move" was "guided by the best scientific advice".

Environmentalists and some farmers' leaders have denounced the cull, but ministers retort that it has worked in bringing down the number of outbreaks.

The new Department for the Environment, Food and Rural Affairs (Defra) says it has "no idea" how many animals have been killed in the "contiguous cull" stretching up to 3km from each infected farm. But it is well over one million; estimates range up to two million.

The cull began in the last week of March, after scientific models predicted that the disease would run out of control for many months, causing alarm in Downing Street.

Dr Kitching told the Independent on Sunday yesterday that he met Mr Brown and Baroness Hayman, a junior agriculture minister, on 29 March and told them that the models were wrong. In early April, he added, he told the interdepartmental science committee on the disease – headed by the Government's Chief Scientist, Professor David King – that "the contiguous cull was unnecessary on the scale at which it occurred".

Dr Kitching – now the director of the Canadian Government's Foreign Animal Disease Laboratory in Winnipeg – visited South Korea, Taiwan and Japan to study outbreaks caused by the same strain of the virus last year, and had begun experiments on it when the British epidemic was first discovered.

The research showed that the virus spread on the wind very much less than had been supposed. This was confirmed in a paper in May by Prof Alex Donaldson, the head of Pirbright, and three other scientists, which concluded that the virus was unlikely to be carried even 200 yards in sufficient quantities to infect other herds.

Dr Kitching said yesterday that Taiwan had "worked out that for this strain there was no need for a contiguous cull". Other nations, such as Japan and South Korea, had also controlled foot and mouth without resorting to it.

But Prof Roy Anderson, of Imperial College, who led one of the groups that produced the models, said that Dr Kitching's had been "a lone voice" when he put his views to the science committee. He said that the extent to which the virus was carried on the wind was "irrelevant" as epidemiologists looked at how much it spread in practice, by whatever means.

Defra admitted that "the airborne spread may prove to be less than originally thought in some of the models" but added that the effect was the same because there had been greater transmission through "poor bio-security".

Senior ministry sources believe that the Government had no option but to order the contiguous cull once faced with the models' predictions, and point out that it has succeeded in dramatically bringing down the rate of infection.

But Dr Kitching retorts: "You could argue that if you slaughtered every susceptible animal in the country you would get rid of it overnight. The argument was: how much culling do you need?"