Image copyright Getty Images Image caption Kim Jong-nam sought help at the airport shortly after his face was smeared with the deadly VX nerve agent

Interpol has issued a "red notice" for four North Koreans wanted in connection with the assassination of the half-brother of North Korea's leader.

Kim Jong-nam was murdered at Kuala Lumpur airport with a lethal nerve agent last month.

Malaysia said the four men were at the airport on the day Mr Kim was killed and had since left the country. They are thought to be in North Korea.

A red notice is the nearest equivalent to an international arrest warrant.

The move is unlikely to result in arrests as North Korea is not a member of Interpol.

Two women - one Vietnamese woman and one Indonesian - have been charged with killing Kim Jong-nam. Both reportedly believed they were participating in a television prank.

Malaysia has not directly blamed North Korea for the assassination, but there is widespread suspicion Pyongyang was behind it.

Investigators have demanded it hand over suspects, three of whom are thought to be hiding in North Korea's embassy in Malaysia.

The four named in the Interpol red notice are Ri Ji Hyon, 33, Hong Song Hac, 34, O Jong Gil, 55, and Ri Jae Nam, 57.

North Korea strongly denies any role in the killing and has demanded that Malaysia turn over Kim Jong-nam's body.

Media playback is unsupported on your device Media caption What happened to Kim Jong-nam: A killing explained

Last week, Malaysia finally formally identified the murder victim as Kim Jong-nam. Authorities say this was done using DNA from one of his children, although they did not say which one.

Malaysia says Mr Kim's body has been embalmed to prevent it from decomposing.

It is not clear where Mr Kim's wife and children are, although his son appeared in a video last week and said the family were together.

Kim Jong-nam, who was the estranged, elder half-brother of Kim Jong-un, had been passed over for the North Korean succession and was living in the Chinese territory of Macau at the time of his death.