In a letter to UN Secretary General Ban Ki-Moon on Wednesday, the rights group says Ibrahim Gambari of Nigeria broke UN rules when he attended the wedding of Chad's President Idriss Deby in Khartoum on January 20, in the presence of Al-Bashir.
"Images of Mr. Gambari embracing President al-Bashir have been widely circulated, showing Darfuri victims that the head of UNAMID socializes with suspected war criminals,'' the letter reads in part.
Al-Bashir is wanted by the International Criminal Court in The Hague for genocide, war crimes and crimes against humanity allegedly committed in Darfur.
"UN guidelines limit UN officials' interactions with individuals indicted by the international criminal courts, such as President al-Bashir, to what is strictly required for carrying out UN mandated activities," says the letter. "Attendance at a wedding ceremony cannot, in our view, be justified as 'strictly required'."
According to Human Rights Watch, UN guidelines specifically state that "the presence of UN representatives in any ceremonial or similar occasion with persons indicted by international criminal courts should be avoided".
The letter asks Ban Ki-Moon to "formally raise these concerns with Mr Gambari and take appropriate action to avoid a repetition of these events".
It rejects a response from the UN Department of Peacekeeping Operations saying that Gambari "attended the wedding at the invitation of President Deby... and had no control over the guest list". "Given the significant likelihood that President al-Bashir would attend the event, proper due diligence on Mr Gambari's part would have avoided this situation, and the resulting harm to Darfur victims and the UN's reputation," writes Human Rights Watch.
President Deby was marrying the daughter of Moussa Hilal, one of the alleged leaders of the notorious Janjaweed militia in Darfur.
© Hirondelle News Agency