Delta and Korean Air have a partnership on routes and networks. Delta increased its stake in Hanjin Kal to 11% as of February 21 from 9.21% as of September 6 for investment purposes, Hanjin Kal said in a regulatory filing.

The stake increase comes amid a family feud between Korean Air's CEO and group chairman Cho Won-tae and his sister, who has joined forces with a local activist fund and a construction firm, ahead of a Hanjin Kal shareholders meeting in March.

(Reporting by Joyce Lee; Editing by Muralikumar Anantharaman)