It may take up to two or three weeks more for the bodies of Malaysians killed in the Malaysia Airlines (MAS) MH17 plane crash in Ukraine to be brought to Malaysia, according to one of the Malaysian investigators of the crash.

Lt Col Mohd Sakri Hussain, principal assistant secretary of the National Security Council, said the delay was because the bodies were not in one piece.

"I feel it may take two or three weeks more before we can expect to receive the bodies," he told reporters at the KL International Airport (KLIA) after his return from Kiev today.

Mohd Sakri was one of the 65 members of the Malaysian team of investigators who returned from Ukraine. Malaysia had sent a team of 116 people to Ukraine on July 18 to help probe the crash of MAS Flight MH17.

The Boeing 777-200 crashed in troubled eastern Ukraine on July 17 while flying from Amsterdam to Kuala Lumpur with 298 people - 283 passengers and 15 crew - on board. It is believed that the plane was shot down.

Asked whether any of the bodies which were in one piece could be brought to Malaysia earlier, Mohd Sakri said the team of investigators found no body in one piece.

"So far, not even one body is in one piece. It must be remembered that the incident took place at 35,000 feet," he said.

He also said 12 Malaysian investigators were still in Kharkiv, Ukraine, to help with the investigation and handle the process of bringing out the rest of the bodies.

"Twelve members of the Malaysian forensics medicine team are still in Kharkiv to help conduct yet another disaster victim identification," he said.

Asked to elaborate on his experience dealing with Alexander Borodai, head of the separatists in Ukraine, he said he was grateful that the Malaysian team received good cooperation from the group.

He said the negotiations went well, so much so that the separatists were prepared to meet, without conditions, Malaysia's request to be given the MH17 black boxes, retrieve the bodies of the passengers and crew and to have complete access to the crash site.

"I spoke with and negotiated with him (Borodai). I asked for the bodies and the belongings to be given to us, the black boxes to be handed to us as it was our aircraft, and for us to have access to the crash site to conduct a probe. He allowed us access to the crash site.

"He agreed to unconditional cooperation, and extended it to us that night itself. I had arrived in the evening, and that night itself we got what we wanted and removed it from the troubled region," he said.

Mohd Sakri praised Prime Minister Datuk Seri Najib Tun Razak for the approach he had employed, giving importance to diplomacy to ensure that national interest took precedence.

"I found that the prime minister's approach was effective in terms of the context, understanding and acceptance. I feel he (Najib) played a significant role in the matter," he said.

Mohd Sakri said that if Malaysia had acceded to the calls to have been firmer in the matter, most probably there would not have been any negotiation that would have had a favourable outcome for the country.