US airstrikes on alleged drug-trafficking boats in the Caribbean Sea are an act of tyranny, Colombia's President Gustavo Petro told the BBC in an interview where he also called for criminal proceedings against US officials if investigations find Colombians were killed in the attacks.

President Donald Trump has cast the strikes, which have reportedly killed 17 since they began this month, as needed to stop the flow of fentanyl and other illegal narcotics into the US.

Legal experts and lawmakers, though, have questioned if they violate international human rights laws.

Why launch a missile if you could simply stop the boat and arrest the crew? said Petro. That's what one would call murder.

Speaking to the BBC on Wednesday, Petro said there should be zero deaths in stopping speedboats believed to be involved in drug smuggling.

He added that the principle of the proportionality of force is violated if you use anything more than a pistol.

The strikes in international waters have primarily focused on Colombia's neighbour Venezuela, according to the Trump administration, but the US has provided little details about the targets and the individuals killed.

Democratic lawmakers in Washington have demanded answers over the legality of the strikes, which United Nations experts have described as extrajudicial executions.

Asked about Petro's comments, the White House stated Trump was prepared to use every element of American power to stop drugs from flooding into our country.

In the interview, Petro further accused the Trump administration of humiliating his people, asserting that South American nations would not bow down to the king.

Trump has recently toughened his stance towards Latin America, including designating several drug-trafficking organizations as terrorist groups.

As tensions rise over the issue, Petro emphasized that Trump is the one isolating the United States with his foreign policies.