GENEVA The top United Nations human rights official called on Spanish authorities on Monday to investigate thoroughly and impartially violence linked to Catalonia's independence referendum, and to hold talks to resolve the secession issue.

Zeid Ra'ad al-Hussein, U.N. High Commissioner for Human Rights, voiced concern at Sunday's violence in which hundreds were injured, saying police responses needed to be "at all times ...proportionate and necessary.

"I firmly believe that the current situation should be resolved through political dialogue, with full respect for democratic freedoms," Zeid said in a statement issued by his Geneva office.

(Reporting by Stephanie Nebehay; editing by John Stonestreet)