The informal group of senior statespeople known as 'the Elders' has criticised the Sri Lankan government over its "clampdown on domestic critics and disdain for human rights".
The network, which includes figures such as Archbishop Emeritus Desmond Tutu, ex-UN chief Kofi Annan, the Dalai Lama, and former US President Jimmy Carter, was speaking about conditions since the end of the civil war between government forces and the Liberation Tigers of Tamil Eelam (LTTE) in 2009.
They have expressed concern over the "deafening global silence" in response to Sri Lanka’s poor human rights record and lack of accountability, warning that impunity may encourage other states to act in a similar way.
On behalf of the group, Dr Tutu declared: "The ongoing persecution and disappearances of human rights activists, journalists and government opponents is truly terrifying."
He added: "Unfortunately, previous internal commissions have done little to reveal the truth behind human rights abuses."
The Nobel Peace Prize laureate went on to urge the current Sri Lankan government to show "greater commitment to achieving meaningful reconciliation".
The Elders particularly highlighted lack of action by the government to address the political marginalisation of ethnic minorities at the root of Sri Lanka’s brutal 30-year war.
They called on the Rajapaksa government to withdraw wartime emergency legislation and make a public commitment to uphold the human rights of all citizens of Sri Lanka, including minorities.
In addition, they demanded that the government co-operate with the UN Secretary-General’s panel of experts on accountability and also permit domestic and international NGOs and media to carry out their work without harassment, intimidation or undue restrictions.
The civil war came to an end last May with the defeat of Tamil Tigers who were fighting for a separate homeland in the North.
The United Nations has estimated that 7,000 civilians were killed and about 250,000 people were displaced from their homes by the conflict.
The Elders were originally formed by former South African President Nelson Mandela to bring together respected independent peace activists and human rights advocates in order to make non-partisan interventions in current situations of conflict and abuse.