The Philippines' Supreme Court has ordered an investigation into four judges whom President Rodrigo Duterte claimed were involved in the drug trade. Despite criticism over his style of crackdown on crimes, Duterte publicly named and shamed several officials in the country alleging their involvement in the drug trade.

The probe order came on Tuesday (9 August), a day after the chief justice condemned the controversial statement by the president in identifying about 160 officials, including seven judges, police officers and soldiers as part of his war on narcotics. On Sunday (7 August) he reportedly ordered all the named officials to surrender or risk being "whacked".

According to Reuters, Supreme Court spokesman Theodore Te said the court has asked a retired judge to carry out an investigation into "the alleged involvement of four incumbent judges". The report is expected in 30 days.

He said the court has decided to treat Duterte's allegations "as a complaint against the four judges".

Four out of seven active judges were given seven days to respond to the allegations. "This is just for the administrative case since the Supreme Court does not have jurisdiction on criminal cases."

The other three judges are not serving the court, with one having been dismissed over a legal issue; another retired last month while the third died eight years ago. None of the judges are believed to have made a public statement yet.

Chief Justice Maria Lourdes Sereno reminded Duterte that only the court can exercise restraint over its judges and other court officers. Duterte admitted that the names given to him might not all be correct, but Sereno has demanded that the president reveal the source who gave him the names and the basis of his allegations against the judges.

Since Duterte took over as president on 30 June, more than 400 people across the country were reportedly killed by police for being suspected drug dealers.

The US government expressed concern over the president's extrajudicial killings and called on the country to ensure that law enforcement does not come in the way of its human rights obligations. In response, Duterte's spokesperson Ernesto Abella said the leader had "repeatedly expressed he does not condone" drug-related killings.

The Filipino interior minister has reportedly ordered the national police chief to investigate such murders, especially those that were believed to have been carried out by vigilantes.