Acknowledging that he had diplomatic immunity, police in Malaysia had initially phrased their interest in questioning Hyon Kwang Song, a second secretary at the North Korean Embassy in Kuala Lumpur, more in terms of a request.

Police attitudes hardened Saturday when they threatened to issue an arrest warrent for Hyon if he did not voluntarily come in for questioning within a "reasonable" time frame,  according to Abdul Samah Mat, the police chief leading the investigation.

"If he failed to turn up... then we will go to the next step by getting a warrant of arrest from the court," Samah told journalists. 

But lawyer Sankara Nair noted that diplomats have immunity privileges even in criminal cases.

"He has immunity no matter a criminal case or otherwise," he said. "Police can apply for a warrant, but it can easily be set aside by the embassy."

Paid $90 for a 'prank'

Meanwhile, one of the two women detained in connection with the February 13 murder at Kuala Lumpur's airport said she was paid $90 (85 euros) for what she thought was a prank, according to an Indonesian official .

Andriano Erwin, Indonesia's deputy ambassador to Malaysia, made the comment Saturday, one day after Malaysian officials revealed that the VX nerve agent was used in the killing of Kim Jong Nam at Kuala Lumpur's airport.

The suspect, Siti Aisyah, 25, also told officials that she did not want her parents to see her in custody.

"She doesn't want her family get sad to see her condition," Erwin said after a 30-minute meeting with Aisyah. "She only delivered a message through us to her father and mother not to be worried and take care of their health."

The two women walked up behind Kim and appeared to rub their hands on his face. They then walked away in opposite directions.

Kim was dead a short time later.

Malaysian police said Aisyah and the other female suspect, a Vietnamese woman who also is in custody, knew what they were doing. Malaysian police said the women were trained to go immediately to the washroom and clean their hands. Both women seen in the video are in custody.

Sweep of the terminal

Malaysian police said that 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, would carry out a sweep of the terminal in the early hours of Sunday morning.

The attack sparked fears in Malaysia that the airport had been contaminated. Officials said there was no danger but the cleaning operation is an apparent concession to public concerns.

VX is an extremely powerful poison, with an amount no larger than a few grains of salt enough to kill.

North Korea hit squad?

The revelation that the VX nerve agent killed Kim has heightened speculation that North Korea had dispatched a hit squad to kill the older half brother of Kim Jong Un.

The assassination also prompted the US to cancel back-channel talks in New York between North Korea and former US officials.

The unofficial meeting planned for next week was abandoned when the State Department refused to issue visas for the North Korean diplomats coming from Pyongyang.

It would have been the first such meeting between the two countries inside the United States in more than five years.

bik/mj (AP, AFP, dpa)