Up to 20 countries worldwide have banned imports of pork and other meat in response to a flu virus that has infected both people and swine, according to documents from the World Health Organization.

While the new H1N1 strain is not food-borne, fears that it may spread through animal products have prompted restrictions on live pigs, pork, cattle, poultry, livestock, feed and animal semen from countries with reported infections, according to the list obtained by Reuters on Monday.

The list was compiled from official statements and media reports. The countries identified as having imposed bans include Russia, China, Croatia, Indonesia, Thailand and Ecuador.

Though Switzerland is on the WHO list, a spokesman for the Swiss Federal Veterinary Office said there are no pork or other meat bans in place in response to the H1N1 virus.

Most of the listed bans affect products from Mexico and the United States and some block imports from Canada, New Zealand, Spain, France, Israel, Costa Rica, El Salvador, Colombia, Cuba, Nicaragua, Panama, Honduras, Guatemala and Dominican Republic.

Global trade in pork meat is worth about $26 billion a year.

The three countries most affected by the bans announced to date — Mexico, the United States and Canada — are among the world's top pork exporters along with the European Union, Brazil, Chile, China and Hong Kong.

The H1N1 virus, which is a mixture of pig, bird and human flus, was originally referred to as "swine flu" despite having infected only people at the time it was discovered.

News about its emergence and spread caused a drop in the market price of hogs and quickly caused Russia, China, Ecuador and other countries to block imports of pigs and pork, despite reassurances from the WTO that they posed no sanitary risks.

The new WHO list shows the number of restrictions has risen.

'NO JUSTIFICATION'

Just days after the WHO announced on Thursday it would change the virus name to "A-H1N1" to clarify it was spreading among humans and not pigs, a Canadian farm worker returning from Mexico was reported to have infected a herd of swine with it.

Before the reported Canadian pig infection was announced, the WTO and three United Nations agencies including the WHO said there was no justification for the imposition of trade restrictions on account of the H1N1 flu.

But on Sunday, a food safety expert said that while pork meat posed no risks, extra precautions should be taken when handling live pigs to avoid spreading and catching the virus that the WHO says is on the brink of causing a pandemic.

"Trading meat, whether processed or raw or frozen meat, should not be restricted because there is virtually no risk of transmission that way," the WHO's Peter Ben Embarek said.

"You might have a risk with the live animals or when slaughtering it, but on the other side, as soon as you are dealing with the final product there is no big risk."

Under international trade rules, countries are allowed to stop imports of goods that are seen to pose health risks or fall short of sanitary standards.

Canada's trade minister Stockwell Day said that governments should "make decisions that are scientifically based".

"This is not an influenza which is carried in the product itself, it's an airborne transmission," he told Reuters in Lithuania.

"We would expect those countries, which have gone ahead with the ban or were thinking about it, would stop and have a look at scientific guidelines and would recognise that the meat itself is not a problem."

The European Union, South Korea, Japan and Kosovo have all said they would avoid any pork import bans for the time being, but several are increasing their monitoring of live pigs and pork products, according to the WHO list.

The other countries listed by the WHO as having imposed pork and meat restrictions are Thailand, Jordan, the Philippines, Ukraine, Lebanon, Azerbaijan, Bahrain, Kazakhstan, Macedonia, Montenegro, Surinam, the United Arab Emirates and Belarus.

In Lebanon, the trade measure involves "destruction of any cargo en route from (flu) affected countries" and also orders the closure of all domestic pig farms, prohibits the slaughter of pigs and calls for "blood testing of all pigs".

Egypt has ordered the slaughter of all its 300,000 to 400,000 pigs as a precaution against H1N1, a move the United Nations said was "a real mistake".