UNITED NATIONS, Oct. 13 - Ukraine on Tuesday defended its decision not to close airspace in the east of the country where a Malaysian passenger plane was shot down, saying it was unaware that anti-aircraft weapons were being used in the area and that planes could be under threat, Reuters reported.

Malaysia Airlines Flight 17 was shot down over eastern Ukraine by a Russian-made Buk missile, the Dutch Safety Board concluded on Tuesday in its final report on the crash in July 2014 that killed all 298 people on board.

The board, which did not lay blame for the air disaster, said Ukraine should have closed the airspace over the conflict zone, and that the 61 airlines that had continued flying there should have recognized the potential danger.

"No one at this time ... was even aware of the presence of highly sophisticated anti-air missile capabilities," Ukraine's Foreign Minister Pavlo Klimkin told reporters during a visit to the United Nations.

"No-one at the time had any kind of awareness of such a threat... everyone was absolutely sure it was about purely conventional weapons," said Klimkin, adding that no efforts would be spared to bring the perpetrators to justice.

In July, Russia vetoed a United Nations Security Council draft resolution that would have set up an international tribunal to prosecute those suspected of downing flight MH17.

Klimkin said Ukraine, Australia, the Netherlands, Malaysia and Belgium - countries who had citizens on board the plane - were considering other options for prosecution. Those countries are conducting a criminal inquiry into the downing of MH17.

He said the countries could return to the U.N. Security Council again to seek its backing for an international tribunal.

"Bringing such a highly sophisticated, extremely dangerous anti-air missile into Donbass is an example of actions which could be and should be treated as an act of terrorism and a war crime," Klimkin said.

A bitter war was raging in eastern Ukraine between Russian-backed separatists and Ukrainian government forces when the aircraft was downed and, amid a huge international outcry, many Western experts and governments immediately blamed the rebels.

Moscow has rejected accusations it supplied the rebels with Buk anti-aircraft missile systems. (rt/ez)