South Korea has said it believes the North Korean regime is involved in the murder of Kim Jong-nam, BBC reports.
North Korean leader Kim Jong-un's half-brother was killed at Malaysia's Kuala Lumpur airport last week.
"We believe the North Korean regime is behind this incident considering five suspects are North Koreans," said Seoul's unification ministry spokesman.
Malaysian police have already detained one North Korean and they say they are looking for four more.
Deputy national police chief Noor Rashid Ismail identified the latest North Korean suspects in a press conference on Sunday.
He said the men left Malaysia last Monday, the day Mr Kim was killed.
"The four suspects are holding normal passports, not diplomatic passports," he said.
Police believe poison was sprayed into Mr Kim's face he waited to board a flight to Macau.