Sri Lanka says it “categorically denies” allegations of war crimes committed by government troops and is questioning the validity of a new documentary purportedly showing such rights violations.

The Sri Lanka High Commission in London Wednesday criticized Britain's Channel 4 for using video supplied by Tamil Tiger rebels or pro-rebel groups in the documentary, “Sri Lanka's Killing Fields.” The video contained footage of what appeared to be the execution of prisoners by government troops.

The government has accused the U.N. and the international community of being duped by a “disinformation” campaign orchestrated by the remnants of the Tamil Tigers.

Earlier Wednesday, the British government pressed Sri Lanka to investigate the allegations. British Foreign Office Minister Alistair Burt said he was shocked by the “horrific scenes” from end of the 25-year war with Tamil Tiger rebels.

Burt said a failure to investigate could lead to international action against Colombo.

The Sri Lanka High Commission says the government has already held more than 200 public hearings for allegations of human rights violations and other charges. It also says if any of the allegations are found to be genuine – even the ones contained in the documentary – it will take action.

The documentary aired Tuesday in Britain.

Since the conflict in Sri Lanka ended in May 2009, Britain has been calling for a thorough, independent probe into claims of war crimes.

More than 7,000 civilians are believed to have died during the Sri Lankan army's final offensive against the Tamil Tigers. At least 80,000 civilians are estimated to have been killed during the conflict that began in 1983.