Sri Lankan President Mahinda Rajapaksa, under pressure from the United Nations and the West to address alleged rights abuses during a nearly three-decade war, ordered an inquiry on Friday into mass disappearances during the war, his office said.
But analysts said any inquiry would have to be credible in order to stave off further criticism of Sri Lanka's human rights record by Western countries and international groups.
Hundreds of people are still missing four years after the end of the war to defeat Tamil separatists in Sri Lanka. Most of the missing are Tamils and the president has resisted calls for an international investigation into what happened to them.
The UN high commissioner for human rights Navi Pillay is to visit Sri Lanka next month and the Commonwealth Heads of Government Meeting (CHOGM) is to take place in Colombo in November.
"The president has directed his secretary to take necessary measures to institute a commission to look into disappearances during the conflict period," presidential spokesman Mohan Samaranayake said.
"It is the (president's) secretary who will decide on the terms of reference, who the members will be, the time frame and so on."
Gomin Dayasiri, a lawyer who backed Rajapaksa during the war, said the decsion was a part of a plan put into into effect to provide an effective response to queries by the UN.
But Dayan Jayan Jayatilleka, a former diplomat and now an independent analyst, said the president was responding to pressure from abroad and any probe would have to be credible.
"The announcement is clearly coincident with the impending visit of United Nations High Commissioner for Human Rights Navi Pillai," he said.
"The move may lack credibility unless the probe is conducted by respected, independent personalities. It cannot be an in-house matter. For instance, it can't be coordinated by the secretary to the president. The credibility is important."
Kusal Perera, director of the Centre for Social Democracy and a government critic, said the move was intended to "concede a few things to get the Commonwealth without much criticism." "But as we all know this commission will be dragged off until the Commonwealth meeting ends and then could disappear."
Calls for independent investigation Rights groups have long called for an independent investigation into alleged war crimes during the final phase of the conflict, which ended in May 2009 with the military crushing the remnants of the Tamil Tiger rebels.
The United Nations in March urged Sri Lanka in a US-sponnsored resolution to carry out credible investigations into killings and disappearances. Many Western nations, including Britain and Canada, have also demanded an independent probe.
The country has a long history of failing to prosecute rights abuses, particularly when members of the security forces were involved, going back to the early 1970s, when the government suppressed a Marxist insurrection.
Local commissions investigating alleged rights abuses have been incomplete or inconclusive.
An expert panel set up by UN secretary-general Ban Ki-moon found the army committed large-scale abuses and that as many as 40,000 civilians were killed in the last months of the conflict. Sri Lanka says these allegations are unfounded.
More than 100,000 people were killed in the war since it broke out in 1983.