KUALA LUMPUR - Prime Minister Najib Razak said on Monday (March 6) that Malaysia's expulsion of North Korea's ambassador showed the country is stern in defending its honour.

"No one should disrupt us as they please," Mr Najib told reporters on the sidelines of the opening of this year's parliament session.

Malaysia expelled North Korean Ambassador Kang Chol on Saturday, giving him 48 hours to leave the country amid a diplomatic spat over the airport murder of Kim Jong Nam, the estranged half-brother of North Korean leader Kim Jong Un.

Mr Kang has to leave Malaysia by 6pm on Monday.

The expulsion by Malaysia came after it demanded a written apology from North Korea over accusations by Mr Kang that Kuala Lumpur was subverting investigations into Mr Kim's murder as part of a political conspiracy with Pyongyang's enemies. The demand was made during a meeting last Tuesday between Wisma Putra officials and a high-level delegation led by former North Korean ambassador to the United Nations Ri Tong Il.

But no such apology was made.

When asked if Malaysia would review its diplomatic ties with North Korea, Mr Najib said "we will take it one step at a time."

A person declared persona non grata in diplomatic terms is barred from entering or remaining in the country. It is the most serious form of disapproval that the country can apply to foreign diplomats.

Mr Kim was killed at the Kuala Lumpur International Airport 2 departure hall on Feb 13 with what Malaysian police said was VX nerve agent, a highly toxic chemical weapon.

The expulsion of the North Korean ambassador comes on the heels of a decision by Kuala Lumpur to rescind visa-free travel for North Koreans to Malaysia.

The North Korean embassy has denied that the man killed was the half-brother of Kim Jong Un, saying instead that he was a North Korean named Kim Chol, based on the passport found on him.

It said the man had a history of heart disease and needed medication for his condition, rejecting autopsy findings that he had been poisoned.

Malaysian Health Minister S. Subramanian, however, said on Monday that based on the autopsy findings, there was no heart attack.