These five persons were among 59 Vietnamese who ran away during their tour of the island, organised by travel firms Hoang Viet Travel-Freight-Investment Joint Stock Company, Vietrantour, Hanoi Red Tours and New World Travel.
These people were allegedly trying to look for illegal employment in the RoK.
The immigration office has found and deported 28 people so far. It continues to search for the other missing people.
The office said it was co-operating with the police and the coast guard to step up inspections to prevent the Vietnamese persons from fleeing to other provinces.
Under a special Act for Jeju Island, all visitors, except nationals from terrorism-linked countries, can enter and stay on the resort island without a visa for up to 30 days, if the purpose of their stay is tourism.
