Ahead of a crucial vote in the UN Human Rights Council in Geneva seeking to censure Sri Lanka on alleged war-time human rights violations, Amnesty International on Tuesday raised the pitch, saying the world body must support an independent international investigation.
In a 63-page report titled, "Locked away: Sri Lanka's security detainees", the international rights group alleged that arbitrary, illegal detention and enforced disappearance were routine in the island nation.
The rights groups have claimed that upto 40,000 civilians were killed in the final stages of the fighting with Tamil Tigers.
"The war crimes alleged in Sri Lanka in the final stages of the war are of such magnitude that if unchallenged risk fundamentally undermining international justice mechanisms --the UN must support an independent international investigation into these alleged crimes," Amnesty said in a release.
"Hundreds of people languish in arbitrary, illegal and often incommunicado detention in Sri Lanka, vulnerable to torture and extrajudicial execution, despite the end of the country's long conflict," it said in the report.
Counter-terrorism legislation allows authorities to arrest people without evidence and to hold them without charge or trial for extended periods. For years, the Lankan government justified this legislation as necessary for combating the Liberation Tigers of Tamil Eelam (LTTE), which was seeking a separate state for the Tamils of Sri Lanka.
"The LTTE had a horrific record of abuse, including killing and imprisoning its critics, but that did not, and does not, excuse the widespread and systematic mistreatment of detainees by the Sri Lankan government," said Sam Zarifi, Amnesty's Asia-Pacific Director.
The report comes amid Lanka's effort to blunt a US move to censure Colombo for alleged rights abuses. Amnesty's Asia-Pacific Director said the security regime that was a hallmark of war "continues after the LTTE's defeat -- little has changed".
"Authorities take advantage of laws allowing them to imprison people for months or years, with no need for prosecution in a court of law," Zarifi said.
He alleged that a lack of accountability or alleged war crimes gives the green light to Sri Lankan authorities to act with impunity. "Meanwhile, the message coming from the Sri Lankan government is that those who dare criticise it risk harassment, or even disappearance."
According to the report, Sri Lankan authorities detain those deemed to be threats to security such as suspected members of armed groups, but they also arrest their families and colleagues. Peaceful critics of the government, including journalists, have been subject to threats and arrest.
It said reports of illegal detentions persist. Since October 2011, 32 people have been "abducted" or subjected to abduction-style arrests that may qualify as enforced disappearances. Many of these people are still missing.
The Sri Lankan Army continues to have a large presence in the north and is deployed for civil policing. The Special Task Force (STF), an elite police commando unit with a history of human rights violations, remains active across the country.
Former detainees have been harassed and rearrested and physically attacked, the report said. Killings and enforced disappearances of newly-released detainees have also been reported, it said.
It said Sri Lanka's constitution prohibits arbitrary detention and torture, in line with international law.
Zarifi said the country's "security regime violates the spirit of its own constitution, while decades of unlawful arrest and detention have damaged the criminal justice system immeasurably".
"If Sri Lanka is serious about ending impunity and committed to reconciling communities torn apart by conflict, the rule of law needs to be a large part of the equation. While governments have the right to address national security concerns, human rights abuses are never justified, the report said