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KUALA LUMPUR, Malaysia — Malaysia's health minister said Sunday autopsy results suggested a nerve agent caused "very serious paralysis" that killed the exiled half brother of North Korea's leader, as police completed a sweep of the budget terminal where he was poisoned and declared it safe of any toxin.

Related: N. Korea Told: Cooperate over Poison Killing or Face Arrest

The investigation has unleashed a serious diplomatic fight between Malaysia and North Korea, a prime suspect in the Feb. 13 killing of Kim Jong Nam at Kuala Lumpur's airport. Friday's revelation by Malaysian police that the banned chemical weapon VX nerve agent was used to kill Kim raised the stakes significantly in a case that has broad geopolitical implications.

A Hazmat team conducts checks inside Kuala Lumpur International Airport 2 airport terminal, where the half-brother of North Korean leader Kim Jong-un, was killed with a highly toxic chemical weapon, according to Malaysian government officials. FAZRY ISMAIL / EPA

Health Minister Subramaniam Sathasivam said the state chemistry department's finding of the VX toxin confirmed the hospital's autopsy result that suggested a "chemical agent caused very serious paralysis" that led to death "in a very short period of time." The VX agent can lead to death very quickly in high doses, he said.

The killing of Kim Jong Nam took place amid crowds of travelers at Kuala Lumpur's airport and appeared to be a well-planned hit. Kim died on the way to a hospital, within hours of the attack.

Tens of thousands of passengers have passed through the airport since the apparent assassination was carried out. No areas were cordoned off, and protective measures were not taken. Subramaniam said there have been no reports so far of anyone else being sickened by the toxin.

Late Saturday, however, police said they would begin a sweep of the budget terminal where Kim was attacked to check for traces of VX.

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The sweep started around 2 a.m. Sunday involving officers from the police's chemical, biological, radiological and nuclear teams, as well as the fire department's hazardous materials unit and the government's atomic energy board. Although VX is not radioactive, police said the radiological team and the atomic energy board were involved as a precaution.

Related: Kim Jong Un's Sibling Was Killed With 'Most Toxic Weapon Ever'

Abdul Samah Mat, the police official leading the investigations, said a two-hour sweep by more than a dozen officers in protective gear detected no hazardous material. He said the budget terminal is "free from any form of contamination of hazardous material" and declared it a "safe zone."

Earlier Saturday, police warned they would issue an arrest warrant for a North Korean diplomat if he refuses to cooperate with the investigation into the attack.

Experts say the nerve agent used to kill Kim was almost certainly produced in a sophisticated state weapons laboratory and is banned under an international treaty. But North Korea never signed the treaty, and it has spent decades developing a complex chemical weapons program.

Kim was not an obvious political threat to his estranged half brother, Kim Jong Un. But he may have been seen as a potential rival in North Korea's dynastic dictatorship, even though he had lived in exile for years. North Korea has denied any role in the attack.

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 acknowledged at the time he has diplomatic immunity and they couldn't compel him to appear.

On Saturday, Malaysia's tone changed.

Related: North Korea Condemns Lone Ally China Publicly for 'First Time'

Abdul Samah, the police official, said authorities would give the diplomat reasonable time to come forward. "And if he failed to turn up ... then we will go to the next step by getting a warrant of arrest from the court," he told reporters.

Lawyer Sankara Nair, however, noted that diplomats have immunity privileges even in criminal cases. Malaysia hasn't directly accused the North Korean government of being behind the attack, but officials have said four North Korean men provided two women with poison to carry it out.

The four men fled Malaysia shortly after the killing, while the women — one from Indonesia and the other Vietnamese — were arrested.

An immigration officer escorts Kim Jong Nam, son of North Korean leader Kim Jong-Il, getting off a bus to board an ANA905 (All Nippon Airways) airplane at Narita airport near Tokyo on May 4, 2001 . Toshifumi Kitamura / AFP - Getty Images, file

Indonesia's deputy ambassador Andriano Erwin told reporters later that Siti Aisyah said she had been paid the equivalent of $90 for what she believed was a harmless prank. Aisyah, 25, said she had been introduced to people who looked like Japanese or Koreans who asked her to play a prank for a reality show, according to Erwin.

Asked if she knew what was on her hands at the time of the attack, Erwin said: "She didn't tell us about that. She only said that it's a kind of oil, baby oil, something like that."

Related: N. Korean Embassy Official Wanted for Questioning in Airport Killing

The Vietnamese woman who was arrested, Doan Thi Huong, also thought she was taking part in a prank, Vietnam's foreign ministry said Saturday.