Last week, the Department for the Environment, Food and Rural Affairs (Defra) was forced to admit that the scientific test results that prompted a panic over the slaughter of the national sheep flock due to BSE infection were fundamentally flawed. The scientist at the centre of the trials, which saw experts study 3,000 cows' brains instead of sheep brains, is now blaming a separate government laboratory for part of the mix-up.

Professor Chris Bostock said that he has received an email from the government's VLA veterinary lab admitting its part in the blunder, and saying that it tested the wrong samples.

Speaking on BBC Radio 4's Farming Today programme, Bostock revealed that he approached the VLA lab last December amid concerns that some of the brains he was studying had become contaminated. It assured him at the time however that there was no bovine contamination in the brains.

Bostock's tests, conducted at the Institute of Animal Health in Edinburgh, had indicated that up to 1% of the national sheep flock was infected with BSE. An investigation is currently underway to establish how the sheep and brain tissue samples became mixed up.