The suspected discovery of the first case of "mad cow" disease in the US has prompted a call for safety checks on imported blood products in the NHS.
One patient died after receiving blood from a vCJD infected donor
As part of efforts to halt the spread of vCJD, the human form of BSE, Britain has sourced all plasma for blood products from the US since 1999.
The Conservatives are now calling on the Food Standards Agency to make checks to ensure blood remains safe.
There is no proof yet that vCJD can be transmitted through blood transfusions.
But the potential danger was highlighted last week when it emerged a patient in a British hospital had died from vCJD after receiving blood from an infected donor.
Tory health spokesman Andrew Lansley said Britain could not halt imports of US blood
products as it would almost certainly be impossible to find
sufficient supplies from a safer source.
But he is calling for action to reassure the public of the safety of the
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
"There is an important issue that arises from this case, which is to try to
maintain the integrity of the American food chain, so we can be sure that
American blood products continue not to be at risk of contamination from BSE,
leading to vCJD," Mr Lansley said.
"Therefore, the two things I am looking for when Parliament returns [on 5 January] are firstly, for us to hear from the FSA that they are working with the Food and
Drug Administration in America to ensure inspection and controls in America are
as good as anywhere, and secondly, to hear from the health secretary [John Reid] what
additional questions he is asking to make sure American blood products are as
safe as we can make them."
Several countries banned US beef imports hours after America announced its first suspected case of BSE.
The move was led by Japan, which bought $800m of US beef last year, and Canada later followed with a partial ban.
COUNTRIES THAT HAVE BANNED US BEEF
Canada - partial ban
Mexico, Brazil, Russia, Ukraine, and a number of Asian counties from Singapore to South Korea were among those who followed Japan's example.
Early on Thursday, China became the latest country to suspend beef products from the US.
The European Union said it was keeping a close eye on the situation, but it has anyway banned most US beef for many years because of growth hormones in the meat.
Tissue samples from the suspected cow are already being studied in the UK, which suffered a devastating outbreak of BSE in the mid-1990s.
The results will be known in a few days' time.
So far, 143 cases of vCJD have been diagnosed in the UK, although the numbers of new cases are falling.
There is no established treatment for the illness, which causes massive brain damage and normally kills within months of being detected.