The three-member Commission will report on the disappearances and abductions of persons during the civil war.
The members are -- Maxwell Paranagama, a retired judge, Suranjana Vidyaratne, who was until recently the director of the Census and Statistics Department and Mano Ramanathan, a Tamil, who had served in the government's reconciliation commission, the LLRC (Lessons Learnt and Reconciliation Commission - a commission of inquiry appointed by President Rajapaksa in May 2010 after the military defeat of the LTTE in 2009.
Rajapaksa's appointment of the probe panel came ahead of a five-day visit by the UN rights chief Navi Pillay from August 25.
She is to monitor progress made by the island nation on human rights ahead of the September sessions of the UNHRC.
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Her visit will take place amid international criticism of Colombo's human rights record during the war against Tamil rebels.
The island has encountered two successive UN Human Rights Council resolutions moved by the US and backed by India.
Both resolutions called for a greater accountability in rights issues with independent investigations into a large number of disappearances.
A government survey conducted in 2012 in the war-torn north said that nearly 8,000 people were killed during the conflict and another 6,350 were missing. However, international rights groups say the figures are much higher.