Men in Sri Lanka are being raped in custody nearly a decade after the civil war, when sexual assault was routinely used to torture detained Tamils, a report said Wednesday.
The rape of men and boys remains widespread but unreported, with victims unwilling to come forward due to social stigma and laws criminalising same-sex relations, the All Survivors Project said in its report.
Rape was rife during Sri Lanka's 37-year civil war, but unlike cases involving women there has been little official record or acknowledgement of men being abused by their captors.
At least 100,000 people were killed during the separatist war between government forces and rebels from the Tamil Tigers group, with atrocities recorded by both sides.
The vast majority of documented cases of male rape both during and after the war were against Tamils, the largest ethnic minority, the report from the US-based research centre said.
"While the full extent of sexual violence against men and boys is not known... sexual violence against men and boys did not stop with the end of the war in May 2009," the report stated.
"Incidents of sexual violence against men continue to be reported during arrests and detentions under the draconian Prevention of Terrorism Act (PTA) which has yet to be repealed or reformed despite commitments to so."
The 40-page report gave graphic details of how male suspects held by police or security forces in the aftermath of the war were subjected to cruel, inhuman and degrading treatment.
In cases documented by rights watchdog International Truth and Justice Project, and referenced in the report, Tamil men were gang raped by Sri Lankan soldiers and subjected to other horrific sexual crimes.
Promises to address Sri Lanka's wartime past have been slow, with the government resisting calls for an internationally-backed tribunal to investigate atrocities against the island's Tamil population.
But the response to the widespread rape of men and boys has "so far been even less adequate" than for other serious human rights violations, the report said.
Homosexuality is illegal in Sri Lanka, discouraging male victims from reporting abuse. Local laws also do not recognise male sexual assault and statutory rape only applies to girls under 16, not boys.
The report's authors urged Sri Lanka to include victims of male sexual violence in its much-delayed official response to war-era abuses.
Sri Lankan President President Maithripala Sirisena came to power in January 2015 with strong backing from Tamils, who bore the brunt of the bloody conflict.
The International Crisis Group this week warned Sri Lanka that its failure to address its wartime past jeopardised any hope of a lasting peace in the ethnically-divided island.