A growing body of evidence collected by UN investigators points to the involvement of senior Syrian officials, including President Bashar Assad, in crimes against humanity and war crimes, the UN's top human rights official said Monday.

Navi Pillay, who heads the UN Office of the High Commissioner for Human Rights, said the scale and viciousness of the abuses being perpetrated by both sides almost defies belief, and is being well documented by an expert UN panel of investigators.

"They've produced massive evidence," she told a news conference. "They point to the fact that the evidence indicates responsibility at the highest level of government, including the head of state."

But Pillay said the lists of suspected criminals are handed to her on a confidential basis and will remain sealed until requested by international or national authorities for a "credible investigation," and then possibly used for prosecution.

Mideast Syria Splintered Opposition

Involvement in war crimes by senior Syrian officials, including President Bashar al-Assad, is indicated by evidence, a UN official said Monday. (The Associated Press)

Pillay said she worries about striking the right balance in determining how long to keep the information secret. The lists "rightly belongs to the people who suffered violations," she said, but they also must be kept sealed "to preserve the presumption of innocence" until proper judicial probes can be done that could lead to trial.

Pillay and the four-member UN panel on Syria war crimes chaired by Brazilian diplomat and scholar Paulo Sergio Pinheiro has previously said Assad's government and supporters and the rebels who oppose them have committed heinous war crimes during the nearly 3-year-old civil war in Syria that has killed more than 100,000 people.

But this time, Pillay specifically referred to the president — though she was careful to say she hadn't singled him out as a possible suspect on the secret lists.

'Talking nonsense'

Syrian Deputy Foreign Minister Faisal Mekdad was dismissive of Pillay's remarks.

"She has been talking nonsense for a long time and we don't listen to her," he told The Associated Press in The Hague.

Pillay said Syria and North Korea — the two countries being probed by a UN investigative panel — represent two of the world's worst human rights violations, but she also cited concerns with Central African Republic, Bangladesh and other regions.

Other places that require the world's attention, she said, are the large-scale expulsions of migrants from Saudi Arabia, the high number of migrant laborer deaths building World Cup stadiums in Qatar, and continuing political exploitation of xenophobia and racism in Europe and other developed regions.