Budapest: On Thursday, Hungary suggested a “biological attack” as a possible source of the country’s first foot-and-mouth disease outbreaks for more than half a century, which has triggered border endings and the mass slip of cattle in the northwest.

Hungary reported a first case of foot-and-mouth disease for over 50 years at a cattle farm in northwestern near the border with Austria and Slovakia last month, the World Organization for Animal Health said, citing Hungarian authorities.

Thousands of cattle had to be removed as the locked country tries to contain the outbreak, while Austria and Slovakia have closed dozens of border crossings after the disease also appeared in southern Slovakia.

“At this point we can say that it cannot be ruled out that the virus was not of natural origin, we may have to do with an artificially constructed virus,” Prime Minister Viktor Orban’s chief of staff, Gergely Gulyas, told a media briefing.

In response to a question, Gulyas said he could not rule out that the virus outbreak was the result of a biological attack without providing information about who might have been responsible.

He also said that suspicion was based on verbal information received from a foreign laboratory and that their findings have not yet been fully proven and documented.

Hungary’s cattle stock numbered 861,000 heads based on a livestock count in December, changed slightly from levels a year earlier. It made up 1.2% of the total cattle stores of the European Union, official statistics showed.

Illness with foot-and-mouth poses no danger to humans, but causes fever and mouth blisters in split ruminants such as cattle, pigs, sheep and goats and outbursts often lead to trade restrictions.

Gulyas told journalists that no new outbreak has been discovered and the authorities continuously took samples.