Samsung Display is in talks with Vietnamese authorities about the additional investment, Yonhap reported without elaborating further.
A Samsung Display spokeswoman declined to comment on the Yonhap report.
A person familiar with the matter told Reuters separately on Tuesday the South Korean panel maker is considering additional investment in Vietnam but did not comment further including on how much the company plans to spend.
Vietnam is a major smartphone manufacturing base for Samsung Electronics and its subsidiaries, which have already invested billions of dollars in the country.
($1 = 1,196.7700 won)