A human rights group has urged Indonesia to involve forensic experts in exhuming mass graves linked to massacres a half-century ago to ensure the preservation of crucial evidence and allow for the identification of bodies.

The statement from New York-based Human Rights Watch comes a month after President Joko "Jokowi" Widodo ordered officials to start documenting mass grave locations for the estimated 500,000-plus victims of the 1965-1966 "anti-communist" massacres.

The government says it will form a team to investigate 122 alleged mass graves compiled by victims' advocacy groups.

Human Rights Watch also called on the government to arrange for security at these sites to prevent unauthorized exhumations. Without forensic experts, exhumations can destroy critical evidence and greatly complicate the identification of bodies, it said in a release received Monday.