The shootdown of the Malaysia Airlines over eastern Ukraine that left 198 people dead may amount to a war crime, the U.N. High Commissioner for human right said Monday.
Navi Pillay, the U.N.'s top human rights official, called for a "prompt, thorough, effective, independent and impartial investigation" of what what she called an "horrendous" incident.
"This violation of international law, given the prevailing circumstances, may amount to a war crime," she told reporters in Geneva, according to the U.N. office.
Flight MH17 was downed while en route to Kuala Lumpur from Amsterdam on July 17. U.S. and Ukrainian officials say it was shot down by a surface-to-air missile from rebel territory, most likely by mistake.
Russia and Russian-backed separatist groups in eastern Ukraine have denied responsibility for the incident.
The bodies of most of the victims were removed from the crash site after several days of delays by separatist groups. The remains were flown to Amsterdam. The largest number of victims were citizens of The Netherlands.
Attempts to send international experts to the crash site to investigate the cause of the shootdown were hampered during the weekend by continued fighting in the area between Ukrainian troops and separatists. Some bodies of the victims still remain in the fields at the huge crash area near the Russian border.
Pillay's remarks coincided with her office's release of its fourth report on the conflict in Ukraine. The latest assessment says at least 1,129 people had been killed and 3,442 wounded as of Saturday, and more than 100,000 have fled the violence since April.
The report by the U.N.'s team of 39 field monitors in Ukraine says there has been an alarming buildup of heavy weaponry in civilian areas of Donetsk and Luhansk — including artillery, tanks, rockets and missiles that are being used to inflict increasing casualties and damage to civilian infrastructure.
The report notes "egregious human rights abuses" in the two locations, which are controlled by the rebels groups.
"There have been hundreds of abductions with many victims tortured," the report says."Increasing numbers of civilians have been killed."
Gianni Magazzeni, head of the U.N. office's branch that oversees Ukraine, said all governments must respect "the presumption of innocence of civilians."
"There is an increase in the use of heavy weaponry in areas that are basically surrounded by public buildings," he said. "All international law needs to be applied and fully respected."