Donetsk insurgent leader Alexander Borodai denied on Saturday that black boxes of the crashed Malaysian airliner MH17 had been found.

Borodai said they had not touched the site where the passenger flight crashed but they reserved the right to begin the process of taking away the bodies since the bodies would decompose in the scorching summer heat.

"We ask the Russian Federation to help us with this problem and send their experts," Borodai, prime minister of the self-proclaimed Donetsk People's Republic, told a press conference.

Borodai said the wreckage of the flight and bodies of the victims scattered over an area of more than 10 square km, which is under the control of insurgents.

Fourteen representatives from the Organization for Security and Cooperation in Europe (OSCE) arrived at the site on Friday to conduct inspection there, he said.

Borodai had held talks with the OSCE representatives and the two sides agreed to set up a security zone at the site in order to facilitate the investigation. Insurgents will guarantee the safety of all the international investigators and do their best to help the probe.

According to information offered by the Ukrainian side, Borodai said, 16 experts from Malaysia and 14 others from Britain are expected to arrive in Kiev on Saturday.

Borodai urged arrival of the experts at the site as early as possible because it is difficult to preserve the bodies of the victims under a temperature soaring over 30 degrees Celsius.

Earlier in the day, Kiev accused insurgents of destroying evidence of crimes from the wreckage of the Malaysian airliner.

"The terrorists have taken 38 bodies to the morgue in Donetsk," the Ukrainian government said in a statement.

Ukrainian Prime Minister Arseniy Yatsenyuk said insurgents in eastern Ukraine barred government experts from collecting evidence and threatened to detain them.

The Boeing 777 passenger plane of the Malaysia Airlines crashed in eastern Ukraine en route from Amsterdam to Kuala Lumpur on Thursday, killing all 298 people aboard.

The Ukrainian government and insurgents in eastern Ukraine traded accusations over the crash. The insurgents said Ukrainian forces shot down the flight, while Kiev said its armed forces did not fire at any flying object in the region where the plane crashed.