UNITED NATIONS, Aug. 8 (Xinhua) -- The United Nations said here Friday that a probe into the downing of Malaysian Airlines flight MH17 is being hampered by the volatile security situation at the crash site in eastern Ukraine.
"While the downing of the aircraft may constitute a war crime, a thorough, effective, independent and impartial investigation is needed to determine the facts and circumstances of this act," Ivan Simonovic, UN assistant secretary-general for human rights, said when he was briefing the UN Security Council on the current situation in eastern Ukraine.
"This investigation is now underway, led by the Netherlands," he said, underscoring that it is disturbing to learn that the volatile security situation at the crash site continues to hamper the investigators, despite the ceasefire zone declared by the government of Ukraine around the area.
"It is urgent to stop the fighting and to secure the crash site, " Simonovic said, adding that at the same time there needs to be accountability for those responsible for war crimes, serious violations of international humanitarian law and gross violations of human rights law, as documented by the findings of the UN Monitoring Mission.
The Boeing 777 went down on July 17 in Ukraine near the Russian border, killing all 298 people on board.
Four Dutch and Australian experts on Thursday last week reached the crash site in eastern Ukraine, said the monitoring mission of the Organization for Security and Cooperation in Europe (OSCE).
Fighting between Ukrainian government forces and pro- independence insurgents in the region had prevented international investigators from reaching the site.
The Ukrainian authorities said on Monday that the international investigation commission pointed to "massive explosive decompression" as a possible cause of the disaster after an examination of the content of the black boxes.
Explosive decompression means the aircraft fuselage suddenly breaks apart, leaving little chance for passengers to survive.