The top United Nations human rights official voiced concern today over the risks to Guineans if the world body launches an investigation into the killing of at least 150 people last month when security forces opened fire on an opposition rally in the West African nation and raped some of the women protesters.

UN High Commissioner for Human Rights Navi Pillay is considering how to assist with an investigation, and make sure that it is credible, in view of the security and political situation on the ground, her spokesperson Rupert Colville told reporters in Geneva.

He said Ms. Pillay is concerned about the harm that Guineans may suffer without the necessary security guarantees for witnesses and those who provide information about the violent suppression of the 28 September demonstration in the capital, Conakry, which she has characterized as a "blood bath."

The timing and format of an investigation mandated from the Office of the High Commissioner for Human Rights (OHCHR) would largely depend on the cooperation of the Guinean authorities, which have announced their own Commission of Inquiry, he added.

For now, Ms. Pillay is gathering information from various sources on the incidents, including the looting of homes of opposition leaders who had been arbitrarily arrested, and considering various models for a possible probe.

Army Captain Moussa Dadis Camara seized power of the West African nation in a coup in December 2008 after the death of Guinea's long-time president Lansana Conté.