Since then the country has spent billions of pounds trying to contain the disease.
Until now all known cases of BSE and the human variant Creutzfeldt-Jakob disease (vCJD) have been reported in Europe, mainly in Britain.
But WHO officials in Geneva are concerned BSE-infected meat in animal feed may have been sold around the world during the delay before European governments began taking measures to stop suspect exports.
"We thought we didn't have a really serious problem and we didn't clamp down on the meat and bonemeal, which is the main route of transmission of BSE, early enough," he told BBC Radio 4's Today programme.
"It is quite right and proper that the WHO is taking this precautionary approach in a sense because once the material has got around it many be many years before you realise that you have a problem.
"You have to act well in advance of actually having cases."
Epidemic fears
In the UK, more than 170,000 cattle have been diagnosed with BSE, compared to around 1,400 in other European countries such as France, Ireland, Portugal and Germany.
Eighty seven British people have died from the brain-wasting vCJD.
There was a 10 year gap between the disease first surfacing in Britain and the beef export ban in 1996.
Since then the country has spent billions of pounds trying to contain the disease.
But the WHO is concerned that poorer nations may not be able to detect or control the disease once it takes hold which could lead to epidemics in cattle and humans in decades to come.
The Chairman of the UK Renderers Association, Brian Rogers, says the warning is entirely plausible.
He said the very stringent controls used to stop the spread of risk material in place in the UK had not been replicated in Europe and other countries.
"In most cases, not at all and in all cases not until recently," he said.
Ministers 'mislead public'
He said the incidence of BSE in other countries may be much lower than in the UK but exports from those regions had continued without being subject to controls.
The WHO warning came as prosecutors in Paris began preliminary investigations into whether to bring manslaughter charges against British and French ministers over deaths linked to mad cow disease.
Earlier, the European Commission threatened to ban some German sausages because of fears they may be contaminated with BSE.