United States expressed support of Malaysia’s intention to continue investigation into serious crimes committed on its territory, in relation to North Korean Kim Jong-nam's murder last month.

In a statement today, US embassy in Malaysia said all possible measures must be taken to bring those responsible for these crimes to justice.

"We are pleased that all Malaysian diplomats and family members who had been barred from leaving the North Korea have been allowed to return to their home country.

"The barred departure of diplomats and their family members was a grave and unacceptable breach of the Vienna Convention," it said.

Nine Malaysians who were barred from leaving North Korea in the aftermath of the Jong-nam's murder arrived at KLIA in a military plane at 5.03am today.

A deal was apparently stitched with Pyongyang in which Jong-nam’s body was sent to North Korea. It was put on board a Malaysian Airlines (MAS) flight bound for Beijing at 7.39pm yesterday.

Prime Minister Najib Abdul Razak in a statement last night announced that the nine were allowed by the North Korean government to return to Malaysia.

Najib, in a posting on Twitter earlier, said: "Alhamdulillah (Praise be to Allah) the special aircraft carrying the nine Malaysians has flown out of North Korean airspace. The diplomatic crisis is over."

Najib said his government strongly believed in the principles of justice and sovereignty.

"Our police investigation into this serious crime on Malaysian soil will continue.

"I have instructed for all possible measures to be taken to bring those responsible for this murder to justice," he said.

Tensions between Kuala Lumpur and Pyongyang arose following the murder of Jong-nam, 46, at KLIA2 on Feb 13.

Two foreign women daubed the face of Jong-nam with the nerve agent VX while he was waiting for a flight to Macau.

Subsequently, Jong-nam was pronounced dead on arrival at Putrajaya Hospital.

On March 1, two women, Siti Aisyah, 25, an Indonesian, and Vietnamese Doan Thi Huong, 29, were charged in the Sepang magistrate's court in relation to the killing.

The diplomatic tiff came about after North Korea's ambassador Kang Chol made wild allegations against Malaysia on how it handled the case, resulting in the government declaring him a persona non grata. He left Kuala Lumpur on March 6.

Pyongyang retaliated by expelling Malaysia's ambassador to North Korea.

On March 7, Pyongyang barred Malaysians in North Korea from leaving that country and Kuala Lumpur took the same action in a tit-for-tat move.