Immigration director-general Datuk Khairul Dzaimee Daud speaks to members of the media in Putrajaya April 22, 2020. — Bernama pic

PUTRAJAYA, Dec 6 — Sabah’s terrain and vast territorial waters are among the main challenges facing the State Immigration Department to curb the entry of undocumented migrants (PATI) into the country,  said Malaysian Immigration Department director-general Datuk Khairul Dzaimee Daud.