North Korea has ordered Malaysia's ambassador out of the country in response to Malaysia's expulsion of North Korea's envoy following the death of Kim Jong Nam in Kuala Lumpur airport.
The North's official Korean Central News Agency said the Malaysian ambassador has been labelled persona non grata and ordered to leave within 48 hours.
On Saturday, Malaysia ordered North Korean Ambassador Kang Chol to depart within 48 hours after he criticised Malaysia's handling of the murder of Kim Jong Nam, the half-brother of North Korean leader Kim Jong Un.
Mr Kang told reporters as he prepared to leave that Malaysia was taking "extreme measures" that would do "great harm" to bilateral relations.
Malaysia had already announced on February 20 that it was recalling its ambassador to North Korea "for consultations".
In an attack believed to have been orchestrated by North Korea, Mr Kim died less than 20 minutes after two women allegedly wiped VX nerve agent on his face at Kuala Lumpur airport on February 13.
The women, one from Vietnam and one from Indonesia, have been charged with murder.
North Korea has denied any role in the killing and accused Malaysia of conspiring with its enemies. North Korean ambassador Kang Chol has rejected a Malaysian post-mortem examination that found Mr Kim was killed with VX, a banned chemical weapon.
Malaysia was protecting its "sovereignty and dignity" by expelling the North Korean ambassador, p rime minister Najib Razak said.
He added that the decision to expel Mr Kang sent a clear message.
"It means that we are firm in defending our sovereignty and dignity," Mr Najib said.
"Don't ever insult our country and don't try to cause disruptions here."
Malaysian foreign ministry spokesman Raja Nushirwan Zainal Abidin said the country's ambassador to North Korea, who was recalled two weeks ago for consultations, was still in Kuala Lumpur. "This reciprocal action is normal in diplomacy," he said.
Malaysia's finding that VX killed Mr Kim boosted speculation that North Korea was somehow behind the attack. Experts say the oily poison was almost certainly produced in a sophisticated state weapons laboratory, and North Korea is widely believed to possess large quantities of chemical weapons, including VX.
North Korea is trying to retrieve Mr Kim's body, but has not acknowledged that the victim is Kim Jong Un's half brother, as Malaysian government officials have confirmed.
Ri Tong Il, a former North Korean deputy ambassador to the United Nations, has said Kim probably died of a heart attack because he suffered from heart disease, diabetes and high blood pressure.
Health minister Subramaniam Sathasivam said pathologists have ruled that out.
"We are saying, based on autopsy findings, there was no heart attack," he told reporters at parliament.
Still, a lawyer for the Vietnamese suspect said news of existing health problems should be cause for a new examination. He also claimed that Malaysian pathologists do not have the expertise in VX.
The two women accused of poisoning Kim say they were duped into thinking they were taking part in a harmless prank.
Malaysia is looking for seven North Korean suspects, four of whom are believed to have left the country on the day of the killing.
The 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.
North Korea has a long history of ordering the killings of people it views as threats to its regime.
Kim Jong Nam was not known to be seeking political power, but his position as eldest son of the family which has ruled North Korea since it was founded could have made him a danger.
The fallout from the diplomatic battle also reached the sports field.
Citing security concerns, Malaysia will not allow its national soccer team to travel to North Korea for a qualifying match for the 2019 Asian Cup, the Football Association of Malaysia said.
Malaysia was due to play North Korea on March 28.
Kang Chol's expulsion "made the current situation unsafe for Malaysians to travel to North Korea for the moment," said the association's secretary-general, Hamidin Mohamad Amin.
The association has asked the Asian Football Confederation to shift the venue from Pyongyang to a neutral arena.