Washington DC - Defense Secretary Pete Hegseth has rejected calls to release a video showing a US "double-tap" strike on a boat in the Caribbean in September, which reportedly killed two survivors of an initial attack.

"In keeping with long-standing department of war policy, Department of Defense policy, of course, we're not going to release a top secret, full unedited video of that to the general public," Hegseth told journalists on Tuesday.

The footage would only be shown to members of appropriate congressional committees, he said.

As part of a killing spree widely condemned as illegal, US forces struck a boat in the Caribbean on September 2. Shortly afterward, orders were reportedly given to kill two survivors, claims that US Admiral Frank Bradley, who was in charge of the operation, has rejected.

The Washington Post reported that two men were clinging to the wreckage when it was struck again and had posed no immediate threat, which would make the killings a blatant violation of both domestic and international legal standards.

Since September, the US military have repeatedly targeted vessels in the Caribbean and eastern Pacific, claiming without evidence that they are carrying drugs.

More than 90 people have been killed in the operations so far.

UN human rights experts have said the operations violate international law, describing the killings as unlawful extrajudicial killings.

Democratic Senator Richard Blumenthal said Tuesday that "the American people need and deserve to see these videos."

"There was, in effect, no specific justification for whatever withholding is occurring, and the failure to provide them, I think, undermines the trust and credibility of this entire operation," he insisted.