Clashes between police and protesters in the St. Louis suburb of Ferguson are reminiscent of the racial violence spawned by apartheid in her native South Africa, the top U.N. human rights official said in an interview Tuesday.

Navi Pillay, who is due to step down at the end of the month after six years, urged U.S. authorities to investigate allegations of brutality and examine the "root causes" of racial discrimination in America.

U.S. lawmakers on Tuesday called for calm and a change in police tactics in Ferguson, Missouri, which has been rocked by clashes after a white officer killed an unarmed black teenager 10 days ago.