A DISPUTE over custody of the body of North Korean leader Kim Jong-Un's half-brother is raging between Malaysia and Pyongyang as inquiries continue into his apparent assassination.

It comes as Malaysian police have announced the arrest of a fourth suspect, a North Korean, over the death of Kim John-Nam.

The man identified as Ri Jong Chol was arrested in Selangor near Kuala Lumpur, police said, giving no other details.

Two women, one of them Indonesian and the other travelling on a Vietnamese passport, and a boyfriend of one of them, had been arrested earlier on suspicion of involvement in the death of Kim Jong-Nam.

South Korea has accused its enemies in North Korea of sending a hit squad to kill Kim Jong-Nam at the airport in Kuala Lumpur, saying two female assassins poisoned him and then fled in a taxi.

Once custody is settled a second post-mortem could be carried out after a senior Malaysian official said the result of the first one was inconclusive.

North Korean Ambassador Kang Chol said Malaysia conducted the first post-mortem "unilaterally and excluding our attendance" and warned that his government will reject any findings.