The disease, which currently has no cure and doesn't affect humans, has recently been reported to have hit Vietnam, Hong Kong, Mongolia, Cambodia, and North Korea.
While the world's largest producer and consumer of pork - China - has culled more than a million pigs since last August to try and stop ASF from spreading, The Financial Timesreport.
'No way to stop it'
"It makes the foot and mouth disease and BSE outbreaks pale in comparison to the damage that is being done. And we have no way to stop it from spreading."
Often referred to as 'pig Ebola' - ASF must be reported to OIE (the World Organization for Animal Health).
'Impossible to control'
However, Pfeiffer added that the pandemic may have spread to neighboring countries 'through pork products brought in illegally from Vietnam and China, even if just by tourists or truck drivers'.
According to The Guardian, Dr Wantanee Kalpravidh, regional manager for UNFAO, said prohibiting the movement of pigs over borders risks creating a 'black market which would be impossible to control'.