Geneva:
The United Nations Human Rights Council (UNHRC) has begun the crucial debate on a US resolution urging Colombo to probe alleged excesses committed during its operation to eradicate LTTE.
The voting holds significance as Prime Minister Dr Manmohan Singh recently made a statement in Parliament that India is inclined to support the resolution which has been moved by Norway, the US and France.
The resolution comes in the background of another Channel 4 documentary allegedly showing LTTE commander Prabhakaran's son with five bullet wounds in his chest, following which Tamil parties pressured the Indian government to support the resolution.
The government has been under huge pressure from its ally, the DMK, which has warned that it could withdraw its ministers from the Cabinet if India either abstained or supported Sri Lanka during the vote.
Sri Lanka's Foreign Minister called External Affairs Minister SM Krishna and asked him to reconsider the decision.
Rights groups say up to 40,000 civilians died in the final months of Colombo's military campaign to crush the Tamil Tigers, who waged a bloody decades-long campaign for a separate homeland for minority Tamils.
The US resolution has been dismissed by Sri Lanka, while activists have accused Colombo-backed elements of "intimidation" against them in Geneva, Switzerland.
Speaking on condition of anonymity, a non-government organisation activist told AFP that while attending the council's meetings, they were photographed by people who appeared to be with the Sri Lanka delegation.
"It was done in a very obvious manner and we felt uncomfortable," said the activist, adding that the team "contemplated leaving the session".
The group brought a complaint to the presidency of the UN Human Rights Council, and later decided to stay as a probe was launched into the matter.
A UN rights spokesman confirmed the complaints and investigation.
"There was a complaint by a number of NGOs that their photographs had been taken," said the spokesman, Rolando Gomez. "We have investigated these incidents, but I can't give more details."
The Sri Lanka mission was not immediately available for comment.
Its chief government whip in Parliament, Water Supply Minister Dinesh Gunawardena, had earlier called the US resolution "ill-timed, ill-conceived and borne out of ignorance".
The US resolution urges Sri Lanka to ensure "justice, equity, accountability and reconciliation" and says Colombo's own probe, the Lessons Learnt and Reconciliation Commission, did not adequately address concerns.
International rights activists said the US resolution was tabled because Sri Lanka has "done too little" to deal with claims of violations during the final months of its conflict with the Tamil Tigers in 2009.
"If adopted, the resolution sends a strong signal to Sri Lanka that it needs to move from cosmetic actions to real steps to hold those responsible for abuses on both sides to account," said Human Rights Watch Geneva director Julie De Rivero.
"By calling for Sri Lanka to urgently present a plan of concrete steps to address accountability, and asking the High Commissioner to assist and report on this process, the HRC will finally provide the many victims of Sri Lanka's long civil war hope of obtaining justice," she added.
The UN estimates some 100,000 people died during Sri Lanka's ethnic conflict between 1972 and 2009.
India, a traditional Sri Lanka ally, signalled on Monday that it was "inclined" to back the US resolution.