Rajapaksa named Desmond de Silva, Geoffrey Nice and Professor David Crane as members of the panel to advice the disappearances panel headed by the former Sri Lankan judge Maxwell Paranagama, a government statement said.
The members of the panel Desmonde Silva and Nice are from Britain while David Crane is a US national.
The disappearances commission was set up by Rajapaksa in August 2013 and mandated to probe the all disappearances of individuals between the time period of 1990 to May 2009 during the military conflict of LTTE.
The commission mandate was later extended to cover the period of the Indian Peace Keeping operation between 1987 and 1990.
The Indian military was invited to station in Sri Lanka's north and east conflict zones then in terms of the Rajiv Gandhi-JR Jayawardene pact widely known as the Indo-Lanka Peace Accord of 1987.
Sri Lankan President has also extended the mandate of the disappearances commission to probe if any person, group or institution had been responsible for any violations of international humanitarian law or international human rights law.
The UN Human Rights Council in late March had mandated the appointment of the international investigation team to probe Sri Lanka s rights accountability.
The move was publicly opposed by Sri Lanka claiming it was impeding its sovereignty and vowed non-cooperation to the work of the UN investigation.
