“This abhorrent act, effectively holding our citizens hostage, is in total disregard of all international law and diplomatic norms,” Najib said in his strongest denunciation yet of Pyongyang since the diplomatic crisis was triggered by the murder of Kim Jong Nam last month.

Najib said his priority now was protecting Malaysians in North Korea, adding that Malaysia “will not hesitate to take all measures necessary when they are threatened”.

“Our hope is for a swift resolution. I call upon the North Korean leadership to immediately allow our citizens to leave to avoid any further escalation.”

Ties between both countries have sunk to their lowest, three weeks after Jong Nam died on Feb 13 following a nerve gas attack believed to have been carried out by two women hired by the North Korean regime.

Both countries sent home their ambassadors, after Malaysia declared Kang Chol, the North Korean ambassador, as persona non grata, for refusing to cooperate with police on Jong Nam’s murder probe.

Kang Chol yesterday left for Beijing, but Malaysian police believe that suspects wanted in connection with Jong Nam’s murder are still hiding in the embassy.

Deputy Home Minister Nur Jazlan Mohamed told reporters outside the bungalow housing the North Korean embassy today that authorities were trying to identify embassy staff.

“We are trying to physically identify all the embassy staff who are here,” he told Reuters, adding that they would not be allowed to leave “until we are satisfied of their numbers and where they are”.

It is believed that there are 11 Malaysians currently in North Korea. A report by AFP estimated some 1,000 North Korean expatriates living in Malaysia. Many are involved in businesses such as computer animation, manufacturing “and some black market activities”, the report said.