Row over Rajapaksa's invitation to India Games ceremony
Activists have criticised India's decision to invite Sri Lanka's president to attend the Commonwealth Games closing ceremony in Delhi.
Sri Lanka's government said President Mahinda Rajapaksa would be the guest of honour at Thursday's event.
The move has angered rights groups and the Tamil diaspora who are critical of Sri Lanka's human rights record.
The Commonwealth Secretariat says the decision to invite Mr Rajapaksa to be chief guest was made by India.
India's invitation is seen by analysts as an attempt to counter increased Chinese influence in Sri Lanka.
The Sri Lankan government is accused of violating international law in its war against the Tamil Tigers (LTTE).
The UN secretary general has appointed a special panel to advise him on "accountability issues" regarding the alleged war crimes committed by both government troops and the LTTE.
Rejecting war crimes accusations, the Sri Lankan government says it has appointed an inquiry panel of its own.
Yolanda Foster of Amnesty International told BBC News that "impunity remains the order of the day" in Sri Lanka despite repeated promises to deliver on accountability.
"Commonwealth countries including India should be at the forefront of supporting an international inquiry into the allegations of violations of international law during the conflict," she said.
India supported the Sri Lankan government's war against the Tamil Tigers and has so far made no comment on the alleged human rights violations.
Delhi has, however, stressed the need for a "meaningful" political settlement of Tamil grievances and the need to resettle the displaced as effectively as possible.
The invitation comes just days after the Commonwealth rejected claims it was advising staff to ignore one of its major founding principals - to protect human rights.
A spokesman for the Commonwealth Secretariat told BBC News that it had nothing to do with the invitation to President Rajapaksa.
Despite its size, the Commonwealth has faced frequent criticism on its track record on protecting human rights.
The Tamil diaspora would like to see Commonwealth members exert pressure on the Sri Lankan government, as they say Britain did in the cases of Zimbabwe and Pakistan.
"The then Shadow Foreign Secretary William Hague told the Global Tamil Forum (GTF) conference in the UK that just because a country has general elections does not necessarily mean that it is following democratic principles," Suren Surendiran, of the GTF, told BBC News.
Sri Lanka is becoming a less democratic country, he said, especially after the latest constitutional amendment that removed the term limits for a sitting president.
"We expect the current foreign secretary to acknowledge that and act accordingly."
Sri Lanka is competing with Australia to host the 2018 Commonwealth Games in Mr Rajapaksa's home town, Hambantota.
Mr Rajapaksa's government lost out in its attempt to host the 2011 Commonwealth summit amid criticism of its human rights record.