Thai authorities prevented 43 people from leaving the country for Finland on Saturday. Officials suspect they were on their way to Finland to pick berries.
The Finnish wild berry industry has been dogged by scandals about the abuse and mistreatment of pickers, who have in previous years come for the summer mainly from Thailand.
The Bangkok Post published the story first, with Helsingin Sanomat the first Finnish outlet to report on the case.
Thai authorities have not granted exit visas for people wanting to pick berries, as they try to negotiate safeguards for people wanting to work in Finland.
Finnish and Thai authorities held a conference by video link on Friday, aimed at reassuring Thai officials that Finland could protect pickers in Finland.
There have been multiple suspicions of corruption and mistreatment in the sector, with some 10 people suspected of crimes connected to berry-pickers' treatment.