Damage to pork exports would be considerable if the disease spread west.

"Even one confirmed infection in the wild boar population would have a decisive impact," warned a ministry of agriculture official.

The National Pig Association (NPA) in the UK reports that there are at least 500 wild boars in Finland, where they are hinted for sport.

Talking about the problem of African swine fever in the European Union (Poland, Latvia and Lithuania) a European Commission official recently told MEPs it was best to let diseased wild boar die naturally.

"Hunting them makes them run, and they will infect others as a result. This will lead to a quicker spreading of the virus. So it's better to manage the population in the location where they are."

Densest populations are close to the Russian border.

Hunting associations oppose eradication.