Rock musician Brian May has promised legal action over the Government's decision to extend the cull of badgers in the face of condemnation from animal rights groups.

Natural England has authorised a four-year licence for Dorset, where b etween 615 and 835 badgers are due to be killed over a six-week period this year, alongside the third of four years of culling in Gloucester and Somerset.

Farming minister George Eustice said "strong action" was needed to protect the dairy and beef industry by controlling the spread of TB in cattle, claiming the support of "leading vets" for the policy.

And farmers' leaders said they were disappointed that the cull had not been extended to other areas.

But critics pointed to an independent expert panel's findings that the trials had proved neither humane nor effective and should be halted, with Queen guitarist May vowing to seek a judicial review of the policy.

Mr May , who founded the Save Me Trust, said: " The Government should quit now, and save the taxpayer more fruitless expense.

"This is a tragedy for our farmers, cattle and wildlife. The scientific advice has been ignored by ministers with more badgers set to die again this year."

Just 274 badgers were killed in the second year of the Gloucestershire pilot, less than 45% of the 615 thought necessary to affect TB rates - something the Government said reflected " extensive unlawful protest and intimidation".

In Somerset, 341 were culled - just inside the target of 316 to 785.

Mr Eustice said the approach "includes strengthening cattle testing and movement controls, vaccinating badgers in the buffer zone around high-risk areas, and culling badgers where the disease is rife".

"Our approach of dealing with the disease in cattle and wildlife has worked overseas and is supported by leading vets."

National Farmers' Union president Meurig Raymond said: "We are very disappointed that more areas will not benefit from it this year. This is much slower progress than we wanted."

The RSPCA was among organisations calling for the cull to be halted and replaced by greater use of vaccination and improved biosecurity.

Assistant director of public affairs David Bowles said: "We are saddened but unsurprised at the restart of the badger culls but to extend the number of cull areas further is alarming.

"The whole scheme has turned into a farce. We have no evidence to show the first two years of culls have reduced bovine TB incidents in cattle and previous studies show that with the numbers killed it may even have made it worse.

"As there have been no new population assessments, target figures for badgers to be killed this year have been simply guessed at, meaning that hundreds of badgers could be killed for a policy that is misguided, inhumane and ineffective."

Shadow environment secretary Maria Eagle accused ministers of a " complete disregard for evidence".

"Following repeated failures to meet deadlines and targets, these so-called 'pilots' have now effectively become an inexpert, unscientific mass cull with no rigorous monitoring or evaluation."