The UN's top rights official began a fact-finding mission to Sri Lanka yesterday after the government dropped public hostility towards her and promised access to former war zones.
Navi Pillay, who has previously been accused by Colombo of overstepping her mandate, arrived in the capital for a week-long mission that will include talks with President Mahinda Rajapakse and visits to the former war zones in the north and east.
Sri Lanka has resisted pressure from the UN and Western nations for a credible investigation into allegations that up to 40,000 civilians were killed in the final months of its separatist war, which ended in 2009.
A no-holds-barred military offensive crushed Tamil Tiger rebels who at the height of their power controlled a third of Sri Lanka's territory. Rajapakse has since been dogged by claims of indiscriminate killing of ethnic Tamils.
During her visit, Pillay is scheduled to hold talks with Sri Lankan rights defenders to discuss the "culture of impunity" that existed over the conflict, local rights activist Nimalka Fernando said.
Tamil groups are banking on Pillay's first visit to Sri Lanka to revive calls for a war crimes probe.
Pillay's visit follows two resolutions by the UN Human Rights Council (UNHRC) in as many years demanding Colombo hold an independent investigation into "credible allegations" that troops shelled hospitals and refugee camps, and executed surrendering rebels.
The government insists that its troops did not kill civilians and has slammed the UNHRC for its "ill-timed and unwarranted" resolutions.
Britain and Australia have asked Sri Lanka to improve its rights record ahead of the Commonwealth meeting, while Canada's Prime Minister Steven Harper has said he will boycott the summit to protest continuing abuses.