In their statement on Tuesday, the eight experts became the latest to add their voices to the growing of criticism of the appointment of Lieutenant General Shavendra Silva, who played a leading role in the brutal end to the 25-year civil war in Sri Lanka in 2009.
The group, which includes the chair of the Working Group on Enforced or Involuntary Disappearances, Bernard Duhaime, and vice chair, Tae-Ung Baik, said: "The appointment of Lieutenant General Silva to the highest ranks in Sri Lankan's Army, while facing allegations of this nature, is an affront to the victims and a harrowing sign of the perpetuation of impunity in the country, which risks undermining the trust of Sri Lankan society on state institutions and fuelling further destabilisation."
Earlier, Secretary-General Antonio Guterres's Spokesperson Stephane Dujarric had expressed concern about Silva's appointment by President Maithripala Sirisena.
UN High Commissioner for Human Rights, Michelle Bachelet said she was "deeply troubled" by his appointment "despite the serious allegations of gross violations of international human rights and humanitarian law against him and his troops during the war."
Silva commanded Sri Lanka's 58th Division during the final stages of the military campaign against the Tamil Tigers in 2009 "and successive UN investigations have implicated his division in alleged serious violations of international humanitarian and human rights law," her office said.
According to a UN investigation, 40,000 people, many of them Tamil civil, were killed in the last days of the war.
(Arul Louis can be reached at arul.l@.in and followed on Twitter @arulouis)
( With inputs from IANS )