The Sri Lankan army said it will agree to investigate war crimes – including executions of prisoners and civilians -- allegedly committed by some of its troops during the final periods of the civil war against Tamil rebels in 2009, following charges made by a British television documentary.

Lieutenant General Jagath Jayasuriya, commander of the army, has appointed a five-member court of inquiry to probe the incendiary charges, the military stated.

If there is a prima facie case disclosed against any person from the evidence led before the Court of Inquiry, a General Court Martial will be convened to try the alleged offenders, the army said.

The army’s sudden volte-face was likely promoted by a warning to days ago from the United States that Sri Lanka would be censured at the United Nations Human Rights Council meeting in Geneva.

The Sri Lankan military has long maintained that it killed no Tamil civilians during the civil war that pitted the Tamil Tiger rebels against the majority Sinhalese government. The conflict lasted 25 years and cost the lives of up to 100,000 people.

However, the Sri Lankan’s government own Lessons Learnt and Reconciliation Commission (LLRC) had already determined that army troops had killed civilians during the war. LLRC urged President Mahinda Rajapakse to enact sweeping reforms, including reforms to the military and wider press freedoms.

The UK documentary, which Sri Lankan army officials previously branded as “fake,” claimed, among other things, that the army killed Tamil civilians even after they had surrendered or had been taken prisoner.

Human rights groups claim that as many as 40,000 civilians were murdered during the final offensive of the war.

Human Rights Watch (HRW) was cautious about the army’s new attitude and hopes that a probe will be meaningful and not just a stunt to prevent a resolution against Sri Lanka next month at the UN Human Rights Council.

HRW group's Asia Director Brad Adams told Agance France Presse: If there is action, it has to encompass not only rank-and-file soldiers but senior officials responsible for giving the orders and creating the policies that led to so many deaths and injuries.”

But Adams added: We'll believe they are serious about accountability when we see people charged for the very serious abuses in the final stages of the war.”