The United States on Monday expressed concern about reports of extrajudicial drug killings in the Philippines and urged President Rodrigo Duterte's government to ensure that law-enforcement efforts "comply with its human rights obligation."

The State Department comment followed the release of Philippines police figures showing there have been about 1,800 drug-related killings since Duterte took office seven weeks ago and launched a war on narcotics, far higher than previously believed.

"We are concerned by reports regarding extrajudicial killings of individuals suspected to have been involved in drug crimes in the Philippines," State Department spokeswoman Anna Richey-Allen said. "The United States believes in the rule of law, due process, and respect for universal human rights, and that these principles promote long-term security."