Philippine coast guard speedboats reached the scene but found one Vietnamese dead and at least six others abducted.
Pirates have attacked a Vietnamese-flagged cargo ship off the southern Philippines, killing one seaman and abducting at least six others in a region notorious for such attacks, officials said Monday.
The MV Giang Hai was attacked by pirates Sunday near the southernmost Philippine island of Baguan near the Malaysian coast, said coast guard spokesman Armand Balilo.
Philippine coast guard speedboats reached the scene but found one Vietnamese dead and at least six others abducted, said military spokesman Colonel Edgard Arevalo.
Arevalo said it was too early to say if the attackers were members of the Abu Sayyaf, a Filipino Muslim extremist group that has been abducting people for ransom in the south for decades.
The waters between Malaysia and the southern Philippines have become increasingly dangerous in recent years as Filipino Muslim extremists have taken to piracy, boarding ships and seizing seamen for ransom.
Maritime officials have warned of an emerging "Somalia-type" situation in the waters if the attacks are not addressed.
Philippine Defence Secretary Delfin Lorenzana said earlier this month that his country plans to ask longstanding defence ally the United States to hold joint exercises in the southern waters.
President Rodrigo Duterte has also urged China to launch patrols off the piracy-plagued waters.
The International Maritime Bureau said in January the number of maritime kidnappings hit a 10-year high in 2016, with waters off the southern Philippines becoming increasingly dangerous.