Sri Lanka's unanswered questions over human rights
23 October 2013 Last updated at 22:49 BST
The BBC has spoken to people in Sri Lanka who say they have been threatened with rape and tortured at the hands of officials.
The group Human Rights Watch says rape and sexual violence are widely used against detainees, something the government denies.
Sri Lanka's Foreign Minister has said the country's investigations into human rights violations have been adequate.
With less than a month to go until the Commonwealth conference in Sri Lanka, the government there has rejected calls for it to co-operate with an international inquiry into human rights violations.
Fergal Keane reports.