Bulgarian border police have detained six migrants who tried to enter the country from Turkey at the Kapitan Andreevo checkpoint.
The six were found during an inspection of a trailer hauled by a car driven by a Turkish national.
All of the migrants were without identity documents on them.
Four, who said they come from Afghanistan - a young man and woman, and two children - are believed to be a family.
The two others are young men who said they are Palestinian.
The six have been detained in the illegal migrants housing facility near Svilengrad.