Simonovic said from Kiev he was challenged by competed narratives about events on the ground in Ukraine since ousted President Viktor Yanukovych suspended talks with the European Union to protect economic ties with Russia.
"Without an independent, objective establishment of the facts and circumstances surrounding alleged human rights violations, there is a serious risk that these competing narratives could be manipulated for political ends, leading to divisiveness and incitement to hatred," he said in a statement. The U.N. team, as an impartial player, will serve to establish the facts, thus helping prevent such manipulation and de-escalate tensions."
More than 75 people died as a result of the political violence that followed the ousted president's decision. Ukrainian authorities were accused of using excessive force, though they justified the reaction on national security grounds.
Simonovic said there are concerns about the strength of the rule of law in Ukraine and impunity for serious human rights violations. He added he's heard "numerous" reports of torture since he arrived in the country last week.
With leaders in the Crimean peninsula of Ukraine moving toward Russia amid lingering military action, Simonovic said he was concerned because "there appears to be no rule of law at present" in the region.
The rights envoy said he was staying in Ukraine until Tuesday to continue his investigation.