The UN rights chief said Monday he was "very disturbed" by the violence during the banned independence referendum in the Spanish region of Catalonia and urged Madrid to investigate any possible misconduct. 

"I am very disturbed by the violence in Catalonia on Sunday... I urge the Spanish authorities to ensure thorough, independent and impartial investigations into all acts of violence," the UN High Commissioner for Human Rights, Zeid Ra'ad Al Hussein, said in a statement.  

"Police responses must at all times be proportionate and necessary."