KUALA LUMPUR (Reuters) - North Korea guaranteed the safety of Malaysians banned from leaving the country, Malaysia’s prime minister said on Thursday, as two Malaysian U.N. employees left the isolated state in a possible sign that diplomatic tensions had begun to settle.

The North Korea flag flutters next to concertina wire at the North Korean embassy in Kuala Lumpur, Malaysia March 9, 2017. REUTERS/Edgar Su

North Korea had barred Malaysians from leaving the country on Tuesday, sparking tit-for-tat action by Malaysia as relations soured over its investigation into the murder last month of Kim Jong Nam, the estranged half-brother of North Korean leader Kim Jong Un.

After earlier this week accusing North Korea of assassinating Kim Jong Nam with a banned chemical weapon and of treating Malaysians like hostages, Malaysian Prime Minister Najib Razak has taken a softer line to get his citizens out of the secretive, nuclear-armed state.

“Diplomatic relations between Malaysia and North Korea will not be severed, as we need to continue communicating with them to find a solution,” Najib said in a statement on his blog.

But, he added that his government “will not relent from a firm approach” in dealings with North Korea.

The departure of two Malaysians working for the U.N.’s World Food Programme (WFP) meant nine still remained at the embassy in Pyongyang. They included three diplomats and six family members.

“The government of North Korea has given a guarantee of safety,” Najib said in a message on social network Twitter. “They are free to do their daily activities, but they cannot leave the country.”

Najib confirmed on Twitter that the two WFP staffers, Stella Lim and Nyanaprakash Muniandy, had left North Korea and reached Beijing.

It was unclear why the pair, who according to a Malaysian government official held U.N. passports, had been allowed to go.

Slideshow ( 4 images )

Malaysian sources familiar with the matter said negotiations were underway between the two countries to resolve their issues, including the removal of the ban on Malaysians leaving North Korea, but were not expected to end soon.

The United Nations has called for calm between Malaysia and North Korea and urged them to settle their differences through “established diplomatic practice.”

Najib said any negotiations with Pyongyang would be conducted behind closed doors.

“I can only disclose that the government is in the process of establishing the reasons and motives behind the actions of North Korea,” he said.

NEGOTIATIONS BEGIN

South Korean intelligence officers say Kim Jong Un had issued standing orders for the elimination of his elder half-brother who was known to have criticized his family’s regime.

Malaysian police have identified eight North Koreans in connection with the case. They say are three still in Kuala Lumpur, hiding at the North Korean embassy.

Malaysia is one of the few countries that has for decades maintained ties with the isolated state. But as relations plunged in the wake of the murder, Malaysia recalled its envoy from Pyongyang and expelled the North Korean ambassador.

A source with direct knowledge of the situation said that no other country was involved in the talks now underway, not even its China, which has friendly relations with both.

“Malaysia has not asked China to get involved,” the source told Reuters. “Malaysia wants to resolve this bilaterally relying on its existing good relations with North Korea.”

Najib said he had spoken by telephone to Mohd Nor Azrin Md Zain, the counselor at the Malaysian embassy in Pyongyang.

“Thank God he, his family and the other Malaysians are safe,” Najib said on Twitter.

Reuters spoke to Nor Azrin earlier in the week.

“We are still here. We have been given the assurance that nothing has changed,” he said.