Galaxy Note 7 smartphones. File pic

A Samsung Electronics Co Ltd investigation into what caused some Galaxy Note 7 smartphones to catch fire has concluded that the battery was the main reason, a person familiar with the matter told Reuters on Monday.

The world's biggest smartphone maker is seeking to put behind it one of the biggest product safety failures in tech history as it prepares to launch the Galaxy S8, one of its flagship phones, sometime in the first half of this year.