United Nations (CNN) -- A video purportedly showing Sri Lankan soldiers executing bound, blindfolded and naked Tamils appears to be authentic, a U.N. investigator said Thursday.
Philip Alston, the U.N.'s Special Rapporteur on extrajudicial, summary, or arbitrary executions, based his findings on a three month, U.N.-backed investigation conducted by three independent forensic experts.
Alston is calling anew for a "genuine and independent investigation" by the Sri Lankan government into war crimes violations allegedly committed by Sri Lankan soldiers against Tamils.
Sri Lanka has previously rejected all calls for independent investigations of alleged war crimes committed during its conflict with Tamil separatists.
Alston said that "as long as there is no investigation undertaken, these allegations are going to continue, the bitterness that they inevitably fuel will continue, and I believe that it (an investigation) is in the interests of the government as well as of others concerned."
Martin Nerisky, spokesman for Secretary-General Ban Ki-moon, said Ban "has informed the government of Sri Lanka that it is considering the appointment of a commission of experts to advise him further and to assist the government in taking measures to address possible violations of international human rights and humanitarian law."
The video in question, showing what appears to be Sri Lankan soldiers firing semi-automatic weapons into at least two captured men until they are lifeless, sparked outrage from human rights groups.
But Sri Lankan government officials called the video a fake and built a case against its veracity using their own forensic experts.
Alston says the independent investigation commissioned by the United Nations rebutted most of the the Sri Lankan findings. He did concede there are some "unexplained elements in the video."
The video was first broadcast by Britain's Channel 4 News in August of 2009.
Sri Lanka's military defeated the Tamil Tiger insurgency in 2009 following a brutal decades-long conflict that killed at least 70,000 people.