The UN human rights chief said on Friday that US military strikes against boats in the Caribbean Sea and eastern Pacific Ocean allegedly carrying illegal drugs from South America are “unacceptable” and must stop.

The UN High Commissioner for Human Rights, Volker Turk, called for an investigation into the strikes, in what appeared to mark the first such condemnation of its kind from a United Nations organisation.

Ravina Shamdasani, a spokeswoman for Turk’s office, relayed his message on Friday at a regular UN briefing: “These attacks and their mounting human cost are unacceptable. The US must halt such attacks and take all measures necessary to prevent the extrajudicial killing of people aboard these boats.”

She said Turk believed “air strikes by the United States of America on boats in the Caribbean and in the Pacific violate international human rights law.”

US President Donald Trump has justified the attacks on the boats as a necessary escalation to stem the flow of drugs into the United States, but the campaign against drug cartels has been divisive among countries in the region.