Malaysian police are to carry out a sweep of the terminal at Kuala Lumpur's airport where North Korean ruler Kim Jong Un's half-brother was killed to check for possible traces of the toxic chemical suspected to have been used in the attack.

A police statement on Saturday said the operation will start at 1am on Sunday.

The check will involve officers from the police's chemical, biological, radiological and nuclear teams, as well as the hazardous materials unit under the fire department and the atomic energy board.

Since the attack on Kim Jong Nam on February 13, tens of thousands of passengers have passed through Kuala Lumpur's airport.

No areas were cordoned off and protective measures were not taken, though officials announced on Friday that the facility would be decontaminated.

The investigation has unleashed a serious diplomatic fight between Malaysia and North Korea, a prime suspect in the death of Kim Jong Nam.

On Friday, Malaysian police said the banned chemical weapon VX nerve agent was used to kill him.

Malaysia said earlier in the week that Hyon Kwang Song, a second secretary at the North Korean Embassy in Kuala Lumpur, was wanted for questioning. But authorities at the time acknowledged that he has diplomatic immunity and that they could not compel him to appear.

On Saturday, Malaysia's tone changed.

Abdul Samah Mat, the police chief leading the investigation, said authorities would give the diplomat "reasonable" time to come forward. If he does not, police will issue a notice compelling him to do so, though diplomats have immunity privileges even in criminal cases

Indonesia's deputy ambassador to Malaysia said the Indonesian suspect in the death of Kim Jong Nam was paid 90 dollars (£72) to help carry out the attack involving VX nerve agent.

But Deputy Ambassador Andriano Erwin repeated Siti Aisyah's previous claim that she was duped into the plot, thinking she was taking part in a prank.

Mr Erwin met Aisyah on Saturday in Malaysia, where the 25-year-old is in custody. Another alleged attacker, a Vietnamese woman, also has been arrested.

According to police, Aisyah rubbed VX nerve agent on the face of Kim Jong Nam amid crowds of travellers. Kim was the older half brother of North Korea's ruler.

Kim Jong Nam, who had been living abroad for years, was approached by the two women as he waited for a flight home to Macau.

In grainy surveillance footage, the women appear to rub something onto his face before walking away in separate directions.

Malaysian police said they had been trained to go immediately to the washroom and clean their hands.

Both women seen in the video are in custody.