The study, conducted in 1994 by the Ministry of Agriculture, Fisheries and Food, found that half of all potentially infected bovine offal - banned from human consumption in 1989 - was going missing from slaughterhouses.
Officials are confident that the offal did not enter the human food supply, but believe it probably was used in animal feed.
The use of cow remnants in feed for other cattle was banned in 1988, after government scientists concluded that this caused the spread of BSE. The failure to police the rules may account for the "BABs" - cows born after the ban, which have become infected.
The BABs, officially numbered at nearly 27,000, have fuelled worries in Europe about British beef. On Wednesday, the Prime Minister said Britain would disrupt European Commission business until it agrees a framework for lifting the ban on British beef.
Details of the Maff study were revealed to a meeting of veterinary surgeons in March by Kevin Taylor, the assistant chief veterinary officer. He said officials calculated how much offal should have been disposed of and incinerated, on the basis of the number of cattle slaughtered, but found only half the expected amount. Since the study, policing of the ban had been tightened up.
But many at the conference questioned his conclusion. One vet said: "No one can have any idea where the missing offal went. It could have gone into the human food supply."
Tory MPs were suggesting last week that European countries are being obstinate over BSE to protect their own beef industries. But European officials are worried that they were too relaxed in the past. European consumers carried on eating potentially infected offal from British cattle even after it was banned from human consumption in the UK.
As a result, according to Dr Stephen Dealler, a consultant microbiologist, France faces an epidemic of Creutzfeldt-Jakob Disease, which has been linked to BSE. He said: "After the offal ban in this country, we simply exported it - mostly to France. It is scandalous."
The EC also delayed banning cattle feed containing cow remnants until June 1994, despite a similar ban being introduced in the UK in July 1988. Britain exported such feed all over the world; even larger amounts were sold overseas after the ban.
Dr Harash Narang, a microbiologist formerly of the government Public Health Laboratory, said: "Exposure of UK cattle to BSE has major implications for the risk of BSE occurring in other countries." He considers it "most likely" that cases outside the UK, such as the 200-plus in Switzerland, have been due to exports of infected cattle or infected feed.