KUALA LUMPUR - Malaysian police are seeking a senior North Korean embassy official in Kuala Lumpur in connection with the murder of the estranged half-brother of North Korean leader Kim Jong Un at the Kuala Lumpur International Airport last week.

At a press conference on Wednesday (Feb 22), Inspector General of Police Tan Sri Khalid Abu Bakar identified the embassy official as Hyon Kwang Song, the second secretary at the embassy.

Mr Kim Jong Nam, 46, was killed at the airport on Feb 13 after two women smeared his face with a poisonous liquid. North Korea has denied that it is behind the attack.

The police chief said besides the embassy official, police are also looking for another two North Koreans. One is a staff member of the North Korean airline, Kim Uk Il, and Ri Ji U. All three men are believed to be still in the country.

He said police have asked the North Korean embassy to allow them to interview the additional suspects.

"We hope the North Korean embassy will cooperate. If not we will compel them to come. We will issue a warrant of arrest," he said, adding that the embassy has so far offered no assistance in the case.

Police have nabbed four people since last Wednesday, including a Vietnamese woman identified as Doan Thi Huong, 28, and an Indonesian woman known as Siti Aisyah, 25. Mr Khalid said police will extend the remand order for the two female suspects.

He said the two women were aware that the substance used on Mr Kim was toxic and had gone to the bathroom to wash their hands after the attack. "We strongly believe it is a planned thing and they have been trained to do that."

Another suspect, the Malaysian boyfriend of Siti Aisyah, Muhammad Farid Jalaluddin, 26, will be released on police bond, he said.

Police have also nabbed a North Korean national, Ri Jong Chol, 46, who has been in Malaysia on a work visa since 2013.

Four other North Korean men wanted by Malaysian police are believed to have left the country on the same day as the attack. Mr Khalid said Malaysian police are seeking the assistance of North Korea to track them down.

He said there was no truth to rumours that Mr Kim's son, Kim Han Sol, was in the country. No family members have come forward to identify the body.

He said that police have stepped up security at the hospital mortuary where Mr Kim's body is being kept after attempts to break into the building.

But he would not give details on those who tried to break in. "We know who they are. No need to tell you," he said.