The United Nations human rights commission has urged the Philippines to launch a murder investigation into President Rodrigo Duterte’s claims he killed three people as mayor of Davao City, and into the killings in his war on drugs, which has led to more than 6,000 deaths.

Since July when Duterte assumed the presidency, there had been 6,000 people killed in the government’s war on drugs, about a third died in police anti-narcotics operations and the rest by motorcycle-riding masked men and vigilante groups.

Duterte told a gathering of businessmen last week that as mayor of Davao City he “personally” killed criminals as he prowled the streets.

He later admitted killing three men, who were involved in a kidnapping case, during a police gunfight in late 1980s.