BEIJING (AP) — The investigation into the death of the exiled half-brother of North Korea's ruler is being conducted in an impartial manner, Malaysia's ambassador to Pyongyang said Tuesday, rejecting accusations from the North that the probe was politically tinged.

Mohamad Nizan Mohamad spoke in China's capital, Beijing, while in transit to Malaysia to where he had been recalled following the death last week in the Southeast Asian nation of Kim Jong Nam.

Kim appeared to have been poisoned at Kuala Lumpur's international airport and police have so far arrested four people carrying identity documents from North Korea, Malaysia, Indonesia and Vietnam. Those arrested include two women who were allegedly seen approaching Kim on Feb. 13 as he stood at a ticketing kiosk at the budget terminal of the Kuala Lumpur airport.

North Korea's ambassador to Malaysia on Monday denounced the country's investigation into Kim's death, calling it politically motivated and demanding a joint probe. Malaysia's foreign ministry responded that the ambassador's comments were "culled from delusions, lies and half-truths."

Malaysian Ambassador Mohamad said the country's investigators were proceeding in a professional manner and would "be very objective and fair to everybody."

"I think the investigation is still ongoing, so just wait and see for that. And we can assure you of the impartiality of the investigation itself because there is no reason for us to be sided with anybody," Mohamad said.

The attack took on added political dimensions when Malaysia refused demands by North Korean diplomats to turn over Kim's body and proceeded with at least one autopsy over the diplomats' objections.

North Korean ambassador to Malaysia Kang Chol told reporters Monday that Malaysia was working in collusion with South Korea as Seoul tries to deflect attention from its own months-long political crisis.

Police "pinned the suspicion on us, and targeted the investigation against us," Kang said. Kang referred to the dead man as "Kim Chol," the name on the passport found with Kim Jong Nam.