The Government has been accused of being "underhand" after ministers admitted an independent audit of the South West badger culls will be limited to their first six weeks.
Farming Minister George Eustice conceded the so-called Independent Expert Panel's remit will not include looking at the extra three weeks of culling in Somerset, and further five weeks in Gloucestershire, which are part of the policy to tackle tuberculosis in cows.
Caroline Lucas, the Green MP who posed the question in the House of Commons, said: "The Government knows that its inhumane policy has no basis in scientific evidence, but is determined to carry on regardless.
"Curtailing independent scrutiny of the cull is an underhand move to push for longer culls.
"It is deliberately restricting the remit of the expert panel as a get-out to justify the failure of the culls. If the panel concludes that culling was not effective, Defra can argue that longer culls are necessary in future.
"It is incredibly disingenous of the Government to seek a get-out to justify pressing ahead with a policy that has been a spectacular failure."
The Independent Expert Panel will advise ministers on whether to extend culling to other areas.
The two "pilots" will be assessed on whether they were safe, humane and effective, and could be rolled out to up to 40 areas to tackle the disease rife in Devon, Cornwall and Somerset.
Both the Somerset and Gloucestershire culls were extended beyond their initial six-week allotted period after marksmen failed to shoot dead 70% of the local badger population. The target is significant as falling short risks spreading the disease further.
During Defra Questions today, the MP for Brighton Pavilion asked: "The remit of the Independent Expert Panel was originally restricted to the planned six-week badger cull period and my understanding is that that remit was not extended when the badger culls were themselves extended.
"Can the Secretary of State reassure the House today that the Independent Expert Panel's scope and report will cover the whole of the culling period and not just the first six weeks, because it is really important that his decisions are informed by wider experience of the whole cull?"
Mr Eustice replied: "The Independent Expert Panel will cover the initial cull period, not the extensions."
In Gloucestershire, only 40% of the local badger population was shot dead by trained marksmen. The Somerset cull was marginally more successful, getting closer at 65%.
A rollout could mean culling in neighbouring Devon and even into Cornwall – both considered bovine TB hotspots.
The disease, said to be spread by badgers, led to the slaughter of 28,000 animals last year – more than 20,000 in the South West – at a cost of £100 million to the taxpayer.