Kim Jong Nam died Feb. 13 at Kuala Lumpur's airport in what Malaysian police say was a well-planned hit by two women who wiped a liquid on Kim's face. Police revealed Friday that the banned chemical weapon VX nerve agent was used to kill Kim, raising the stakes in the case.

Health Minister Subramaniam Sathasivam said the dose of VX given to Kim was so high that he showed symptoms within minutes. Kim fainted at the airport clinic and died in the ambulance while en route to a hospital, he said.

"VX only requires 10 milligrams to be absorbed into the system to be lethal, so I presume that the amount of dose that went in is more than that," he said at a news conference. "The doses were so high and it did it so fast and all over the body, so it would have affected his heart, it would have affected his lungs, it would have affected everything."

Asked how long it took for Kim to die after he was attacked, Subramaniam said, "I would think it was about, from the time of onset, from the time of application, 15-20 minutes."

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 on the same day as the killing, while the women — one from Indonesia and the other Vietnamese — were arrested.

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 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.

AP