The broadcaster's film 'Sri Lanka's Killing Fields' shown last night was described by presenter Jon Snow as "one of the most important" stories he has ever reported, and one of the most shocking ever screened on Channel 4.
The investigation into the final weeks of Sri Lanka's 25 year long civil war claimed to show "executions, atrocities and the shelling of civilians".
In a statement this morning Foreign Office minister Alistair Burt said he was shocked by the scenes.
"The recent UN Panel of Experts' report, this documentary and previously authenticated Channel 4 footage, constitutes convincing evidence of violations of international humanitarian and human rights law.
"The whole of the international community will expect the Sri Lankans to give a serious and full response to this evidence.
"Since the end of the conflict the UK has called for an independent, thorough and credible investigation of the allegations that war crimes were committed during the hostilities and the UK Government expects to see progress by the end of the year. I reiterated this message to the Sri Lankan Foreign Minister on 14 June.
"If the Sri Lankan government does not respond we will support the international community in revisiting all options available to press the Sri Lankan Government to fulfil its obligations.
"Unless this is done, Sri Lanka will not be able to move on, and the prospects for reconciliation between Sri Lanka's communities will be curtailed. It is of the greatest importance that this does not happen."
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