New evidence of human rights abuses committed by the Sri Lankan government during the last stages of the war last year have been uncovered by the New York based global rights monitor Human Rights Watch (HRW).

The evidence lead HRW to call for “an independent international investigation into violations of the laws of war” in a report released on its website.

HRW obtained evidence for these allegations of war crimes through first hand witness accounts through video and photo evidence obtained from Sri Lankan Army soldiers.

The organisation claimed it received over 200 photographs taken on mobile phones by members of the Sri Lankan Army’s Air Mobile Brigade on the frontlines of the battle zone in 2009.

One incident documented is the killing of a man, identified by independent sources as a member of the LTTE’s political wing from Jaffna.

In the sequential photos the man is shown first sitting and tied to a palm tree. His chest is covered in blood and his arm is in a sling, suggesting serious injury.

He is surrounded by men in military uniform, one of whom is brandishing a knife in the victims face.

In other pictures the victim is now seen in a ditch, clearly dead, covered in more blood. He is draped in a blood stained flag of Tamil Eelam.

There is material visible on his neck, which appears to originate from the back of his head.

This is “consistent in colour with brain matter which would indicate an injury to the back of his head, as nothing is visible which would cause this on his face,” said an analysis by an independent forensic analyst.

“This would indicate severe trauma to the back of the head consistent with something like a gunshot wound or massive blows to the back of the head with something such as a machete or axe," the expert said.

The evidence all but proves that the victim was tortured and then executed, said the HRW report.

Further pictures show several women in LTTE uniforms with their clothes partly removed, raising concern that there may have been sexual abuse or mutilation.

HRW states that these pictures don’t give conclusive evidence but highlight the necessity for an independent international investigation into alleged war crimes.

The report further describes witness accounts describing indiscriminate artillery barrages on civilian gatherings, including the shelling of a queue of women and children waiting for food distribution.

The report also documents witnesses who described forced recruitment by the LTTE.

HRW further highlights the failure of the government of Sri Lanka to investigate human rights abuses and war crimes allegations, and challenges the delay by the UN to launch its own investigation.

"[UN Secretary General] Ban's inaction is sending a signal to abusers that simply announcing meaningless commissions and making loud noises can block all efforts for real justice. The only way to ensure accountability in Sri Lanka is to establish an independent international investigation," Acting Asia director of HRW, Elaine Pearson said.