Police are seeking four more North Korean suspects in relations to the murder of Kim Jong-nam, the older half-brother of North Korean ruler Kim Jong-un.

Deputy inspector-general of police Noor Rashid Ibrahim said the four, all males, were believed to have left the country on Feb 13 - the day Jong-nam was murdered.

The four wanted suspects are Ri Ji Hyon, 33, Hong Song Hac, 34, O Jong Gil, 55 and Ri Jae Nam, 57, who all entered Malaysia on separate days between Jan 31 and Feb 7.

Noor Rashid declined to disclose their destination countries, but said the police would work with Interpol to track them down.

"The case will be referred to the public prosecutor for further instructions and investigation.

"We seek the public's assistance in Malaysia and those who have the information pertaining what I have stated earlier to call us, or the embassy, so that we can complete the investigation," he said at the police's first press conference regarding the murder.

Three other persons of interest

Police are also looking for another three males to assist investigations, including a Ri Ji U who also went by the name James.

The names of the other two individuals are unknown and their identities are being established, but the police are in possession of their photographs.

Police have thus far arrested a Vietnamese woman, an Indonesian woman, a Malaysian man and a North Korean man in connection with the murder.

Noor Rashid also urged Jong-nam's next-of-kin to come forward and identify the body. They would be given until Feb 27 to do so.

Noor Rashid said no one has come forward, which is identified as Kim Chol by his travel documents. Police are still attempting to contact the deceased's next-of-kin, and have sent his passport to the North Korean embassy for verification.

He said procedures require the body to be identified by next-of-kin, whose relation with the deceased would be verified by methods such as DNA analysis.

"I would like to reiterate here this evening that we have to confirm the people who come forward, so they would have to produce evidence or facts pertaining to their identity and convince us who they are, what are their relations with the deceased, so on and so forth.

"Only when we are satisfied would we proceed with the next action. This is because the identification of the body is very vital to the investigation," he said.

To a question on what would happen if no one claims the body, Noor Rashid said: "I have given the time frame. If they still don’t come forward, they we will look for the next option.

"I don't want to disclose it (the next option) at the moment. We will wait and see."

Toxicology report pending

He added that a post-mortem had been performed on Feb 15, but cause of death is still yet to determined, pending a toxicology report and a pathology report.

Noor Rashid said the deceased had approached the customer service counter at the KLIA2 airport terminal at about 9am on Feb 13, to complain that two unidentified women had sprayed or wiped his face with a liquid and that he was feeling dizzy.

He was sent brought to a clinic and later sent to Putrajaya Hospital, but was pronounced dead upon arrival at about 11am.