Vidmantas Paulauskas, deputy director of the Lithuanian State Food and Veterinary Service (LSFVS), said this was theoretically possible, but the infection could have come from Ukraine, Russia or other countries, too.

"It's a bit strange to hear it being blamed solely on the Baltic states," he told BNS.

Belgium's public broadcaster RTBF reported on Sunday that the country's authorities were looking at two main possible explanations for the source of the infection. One is that the virus came with food waste thrown away by Baltic truck drivers and the other is that it was brought by Belgian soldiers who returned from missions in the Baltic countries.

"The hypothesis that drivers may carry an infection with home-made food to other countries is probable. But it may as well come from Ukraine, Russia or, possibly, other affected countries. Why from the Baltics? Ukrainian and Russian drivers may bring it as well," he said.

Detailed research needs to be done before making conclusions, he added.

The largest number of ASF outbreaks in Europe has been registered in Poland (1,960), followed by Lithuania (1,260), Latvia (559), Estonia (198), Romania (60) and Hungary (35).