Russia has suspended imports of American beef products after the US announced its first suspected case of BSE or "mad cow disease".
Tissue samples from the suspected cow are being studied in the UK
Ukraine, South Africa and a number of Asian countries also halted imports after receiving confirmation from the US of the case in Washington state.
The European Union, which already has bans on some US beef because of growth hormones fears, is not planning a ban.
A spokeswoman said the EU would keep "a very close eye on the situation".
"We have had a number of restrictive measures in place for a long time. For the moment there are no plans to change that," she said.
Tissue samples from the suspected cow are being studied in the UK, which suffered a devastating outbreak of mad cow disease in the mid-1990s.
BOVINE SPONGIFORM ENCEPHALOPATHY
First surfaced mid-1980s
Can pass to humans through infected beef products
Human form of disease called vCJD
vCJD has killed 137 people, mainly in the UK
The results will be known in a few days' time.
A spokesman for the UK's Meat and Livestock Commission said the discovery was
"We sympathise with the industry in the USA, however they have got a number
of important measures in place to ensure that their consumers are adequately
protected," he said.
"Any consumers in this country who have any concerns should look for the
British label which is clearly marked on the packaging."
According to figures released by the commission, Britain imported only 15
tonnes of beef from the US up to September this year.
BSE has been linked to new variant Creutzfeldt-Jakob Disease (vCJD), a human brain-wasting disease.