Sri Lanka's president in an interview published Saturday firmly denied that government troops executed the 12-year-old son of separatist chief Velupillai Prabhakaran in 2009.

Britain's Channel 4 released photos last week to publicise their new documentary, "No Fire Zone -- The Killing Fields of Sri Lanka" alleging that soldiers had killed the slain Tamil Tiger chief's youngest son Balachandran.

But President Mahinda Rajapakse strongly rejected the allegation made in the documentary, which was shown at the UN Human Rights Council in Geneva on Friday.

"Had it happened, I would have known (it). It is obvious that if somebody (from the armed forces) had done that, I must take responsibility. We completely deny it," the president told India's Hindu newspaper. "It can't be."

Sri Lanka claimed victory over the Tamil Tigers after the May 2009 killing of Prabhakaran and his top commanders.

The government in the past has maintained that Prabhakaran's family were killed in the fighting. However, the bodies of his wife and daughter have never been found.

In one photograph released by Channel 4, Balachandran is seen eating a snack while sitting in a green sandbag bunker guarded by a soldier. A second image shows his bullet-riddled bare-chested body.

Director Callum Macrae, also writing in the Hindu newspaper last week, said the photos used in his documentary proved the army's involvement in war crimes, including summary executions during the island's 37-year-long civil war.

Rights groups say up to 40,000 civilians were killed by security forces in the final months of a no-holds-barred offensive in 2009 that ended Sri Lanka's decades-long fight against Tamil separatists.

Sri Lanka denies causing civilian deaths, but Colombo faces a fresh censure resolution at the ongoing UN Human Rights Council session later this month.

Rajapakse accused international human rights organisations and media outlets of being very one-sided over allegations of human rights abuses in the final stages of the war in 2009.

"They must not merely listen to one group and the opposition (in Sri Lanka).

Rajapakse accused Sri Lanka's opposition of "trying to get the support of other countries to create an Arab Spring'" uprising in the resort island nation. "That won't happen in Sri Lanka," he said.