Outgoing U.N. rights chief Navi Pillay rebuked the U.N. Security Council on Thursday for putting short-term geopolitical concerns and narrowly-defined national interests ahead of stopping mass atrocities and grave breaches of global peace and security.

"I firmly believe that greater responsiveness by this council would have saved hundreds of thousands of lives," Pillay told the 15-member body during her final briefing after six years as the U.N. High Commissioner for Human Rights. Her term ends on Aug. 30.

Pillay spoke at a meeting where the Security Council unanimously adopted a resolution promising more aggressive efforts to prevent conflicts.

British U.N. Ambassador Mark Lyall Grant, president of the council for August, said the body needed to "to switch from a culture of reaction to a mindset of conflict prevention."

However, the resolution said little about the political differences that often paralyze the Security Council, where sharp divisions between veto-wielding members Russia and the United States have often thwarted action on Syria and Ukraine.

Pillay touched on the problem in her remarks.

"Short-term geopolitical considerations and national interest, narrowly defined, have repeatedly taken precedence over intolerable human suffering and grave breaches of — and long-term threats to — international peace and security," she said.

She enumerated crises in Afghanistan, Central African Republic, Democratic Republic of Congo, Iraq, Libya, Mali, Gaza, Somalia, South Sudan and Sudan and said they "hammer home" the international community's failure to prevent conflict.

Pillay pointed to Syria’s conflict saying it "is metastasizing outwards in an uncontrollable process whose eventual limits we cannot predict."