The North Korean ambassador expelled by Malaysia in a row over the investigation into the murder of the North Korean leader's half-brother said Monday the Malaysian government's actions had harmed bilateral ties.

"I express grave concern over the extreme measures taken by the Malaysian government, doing great harm to the bilateral relations," Ambassador Kang Chol told reporters at Kuala Lumpur International Airport as he prepared to leave the country.

Malaysia gave Kang 48 hours to leave and declared him "persona non grata" on Saturday, following his failure to apologize for saying last month that North Korea cannot trust the Malaysian investigation into the death of Kim Jong-nam on Feb. 13. He had also accused Malaysia of "colluding with outside forces."

Kim was killed at Kuala Lumpur International Airport after two women allegedly smeared his face with VX, a nerve agent classified by the United Nations as a weapon of mass destruction. Indonesian Siti Aishah and Vietnamese woman Doan Thi Huong remain in custody, charged in connection with Kim's death.

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

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

"Malaysia will react strongly against any insults made against it or any attempt to tarnish its reputation."

U.S. and South Korean officials have said Kim was killed by agents of North Korea.

Malaysia released a suspect from North Korea on Friday for lack of evidence connecting him to the attack, but are looking for four other North Korean suspects.