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Malaysia on Saturday moved to expel the North Korean ambassador, escalating a diplomatic row between the two countries over the murder of the estranged half-brother of North Korean leader Kim Jong Un.

Ambassador Kang Chol was declared "persona non grata" and asked to leave Malaysia within 48 hours.

Kim Jong Nam, the leader's half-brother, was murdered on Feb. 13 at Kuala Lumpur International Airport, after being assaulted by two women — one Indonesian, one Vietnamese — who Malaysian police believe smeared his face with VX, a nerve agent classified by the United Nations as a weapon of mass destruction.

Kim Jong Nam in 2007. Jiji Press via AFP - Getty Images

The ambassador had said last month that Pyongyang "cannot trust" Malaysia's handling of the investigation.

Malaysian Prime Minister Najib Razak called the comments "diplomatically rude."

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Foreign Minister Anifah Haji Aman said in a statement on Saturday that Malaysia had demanded an apology from the ambassador, but none was forthcoming.

Embassy officials also failed to turn up for a meeting Saturday at the foreign ministry, so Malaysia decided to expel the ambassador.

Related: Kim Jong Nam Killing: Malaysia Condemns Use of Chemical Weapon

"It should be made clear — Malaysia will react strongly against any insults made against it or any attempt to tarnish its reputation," Anifah said.

Earlier Saturday, a North Korean chemist deported from Malaysia accused police of threatening to kill his family unless he confessed to Kim's assassination, calling it a plot to tarnish his country's honor.

North Korea's Ambassador to Malaysia Kang Chol speaks to the media outside the North Korean Embassy in Kuala Lumpur on Feb. 20. Vincent Thian / AP

Ri Jong Chol spoke to reporters in Beijing while on his way to Pyongyang. Malaysian authorities have said there's insufficient evidence to charge Ri who said he worked in Malaysia trading ingredients needed for soap.

He was detained four days after the attack but police never revealed what they believed his role was.

Ri said he wasn't at the airport the day Kim was killed but that police accused him of being a mastermind and presented him with "fake evidence." He said they showed him a picture of his wife and two children, who were staying with him in Kuala Lumpur, and threatened to kill them.

"These men kept telling me to admit to the crime, and if not, my whole family would be killed, and you too won't be safe. If you accept everything, you can live a good life in Malaysia,"Ri said."This is when I realized that it was a trap ... they were plotting to tarnish my country's reputation."

National police chief Khalid Abu Bakar said he will hold a press conference on Tuesday to respond to Ri's comments. Meanwhile, immigration Director-General Mustafar Ali said Friday that Ri has been blacklisted from re-entering Malaysia.

Malaysia is looking for seven other North Korean suspects, four of whom are believed to have left the country on the day of the killing. Three others, including an official at the North Korean Embassy and an employee of Air Koryo, North Korea's national carrier, are believed to still be in Malaysia.

Police on Friday issued an arrest warrant for the Air Koryo employee, Kim Uk Il, but didn't say why he is a suspect.

Kim Jong Nam's death has unleashed a diplomatic battle between Malaysia and North Korea. Malaysia said it was scrapping visa-free entry for North Koreans on Thursday while the Foreign Ministry said in a statement it was "greatly concerned" about the use of the VX nerve agent.