"The Government has quietly introduced tough powers to seize and slaughter farm animals against their owners' wishes.
The move comes only three weeks after the House of Lords defeated similar measures in the Animal Health Bill.
It gives Government officers the power to cull any cow, sheep, goat or cat - whether healthy or not - and impose a penalty of up to two years' imprisonment on any owner who obstructs Government inspectors in their work.
Previously, inspectors had to have reason to suspect the presence of a transmissible spongiform disease, such as BSE or scrapie.
Now they can use "reasonable force" to enter any premises housing any "TSE susceptible animal" and slaughter all animals.
The powers also give inspectors, and any "other persons as he considers necessary", such as police, Army or slaughtermen, powers to seize computers or records.
The new regulations came to light last night hidden among legislation designed to assess the spread of scrapie in sheep. They were published shortly before Easter by the Department for Environment, Food and Rural Affairs and came into force on April 19.
Under Commons procedures, MPs have until the end of next week to debate the legislation, contained in a statutory instrument, before it automatically becomes law.
MPs can seek a debate to annul the regulations through a motion known as a prayer, but this does not allow for amendments to be tabled and would mean either rejecting or accepting the entire 220-page document.
The Lords will be given no opportunity to debate or vote on the legislation. On March 26, peers rejected the Animal Health Bill after questioning the Government's attempts to rush through similar laws covering future outbreaks of animal diseases before two further Government inquiries into the foot and mouth outbreak report this summer.
After peers rejected the Animal Health Bill, Lord Whitty, the farming minister, said there might be "other channels" the Government could use to introduce powers to enter farms and slaughter animals at will. These measures appear to be one such channel.
The legislation will be debated on May 15, but opponents pointed out it is unlikely to be defeated given the Government's large majority.
Peter Ainsworth, the shadow rural affairs secretary, said the legislation would "give the Government an inappropriate extension of its powers".
He went on: "We are all in favour of measures to eliminate scrapie but very few people are going to be in favour of measures that will allow officials to kill just about any farm animal except the dog."
Barney Holbeche, parliamentary affairs official at the National Farmers' Union, said he could see that "Government officials might need the powers in extreme circumstances" but was concerned that there was a balance to be struck.
"Clearly there are individual rights that might be infringed under the measures of stamping disease out."
A Defra spokesman said that the new legislation in the statutory instrument had been "put out for consultation last August, before the Animal Health Bill came into being".
He added: "It is a more robust package of BSE and scrapie measures designed to bring us into line with EU regulations."