The possible identification of the man, seen in about 200 images depicting abuse, comes after Interpol released a photograph of the suspect.
The pictures of the man were digitally altered but police computer specialists have produced identifiable images.
Police said they may have been taken in Vietnam and Cambodia in 2002 and 2003.
The suspected child abuser was identified by five different sources from three continents as a man teaching English at a school in South Korea, Interpol said
His name, nationality, date of birth, passport number, and current and previous places of work have also been established, according to the international police organisation.
'All other means'
Interpol said that on Thursday the man flew from Seoul to Bangkok International Airport, where his image was captured by security cameras.
The man seen, apparently abusing 12 boys in a number of images, was a danger to children while he remained at large.
The international police organisation launched its unprecedented global public appeal last week, after trying "all other means" to identify the man.
It said more than 200 people had responded to their appeal.
The first pictures of the man were found three years ago in Germany and the search for the suspect had been codenamed Operation Vico.
The pictures had been manipulated to disguise the man's face with a swirl pattern, but computer specialists at Germany's federal police agency, the BKA, worked with Interpol's human trafficking team to produce identifiable images.
Interpol maintains a database of 520,000 images of child sex abuse submitted by 36 member states.
Using sophisticated software, investigators have identified and rescued nearly 600 victims from 31 countries.