Rupert Colville, spokesman for the U.N. High Commissioner for Human Rights, says the team's 10-day mission began Tuesday.
He told reporters Tuesday in Geneva that the attack was "clearly ethnically motivated."
An angry mob of about 300 stormed the Nahibly camp Friday near the western town of Duekoue. Along with the dead, 67 people were injured.
The attack came a day after the killing of four residents of Duekoue, which locals blamed on camp dwellers.
The four residents killed belonged to the ethnic group that largely backed President Alassane Ouattara. The camp mostly houses supporters of Laurent Gbagbo, the ousted president.