The Philippines has recorded about 1,800 drug-related killings since President Rodrigo Duterte took office seven weeks ago and launched a war on narcotics.
The United States, a close ally of the Philippines, said it was “deeply concerned” by the reports.
Police were also investigating 1,067 other drug-related killings. Earlier President Duterte railed against the United Nations for criticising the wave of deaths.
Duterte said in a strongly worded conference said that the Philippines might leave the United Nations and invite China and others to form a new global forum, accusing it of failing to fulfil its mandate.
Last week, two U.N. human rights experts urged Philippines to stop the extra-judicial executions and killings.