US lawmakers are pressing the Trump administration for answers about military strikes on suspected Venezuelan drug boats, following reports that a follow-up strike was ordered to kill survivors of an initial attack.

Republican-led committees overseeing the Pentagon have vowed to conduct 'vigorous oversight' into the US boat strikes in the Caribbean, following the report.

On Friday, The Washington Post reported that a US strike on a boat on 2 September left two survivors, but a second attack was carried out to comply with Defence Secretary Pete Hegseth's orders to 'kill everybody' on board.

Hegseth decried the report as 'fake news' and President Donald Trump said he believed him '100%'.

The US has expanded its military presence in the Caribbean and carried out a series of lethal strikes on suspected drug-smuggling boats in international waters off Venezuela and Colombia, as part of what it calls an anti-narcotics operation.

More than 80 people have been killed since early September.

The Trump administration claims it is acting in self-defense by destroying boats carrying illicit drugs to the US.

In its report, The Washington Post stated that Secretary Hegseth 'gave a spoken directive' to 'kill everybody' on board one vessel, prompting a Special Operations commander to order a follow-up strike.

Lawmakers from both parties expressed concern on Sunday talk shows, stating that if the reports regarding the follow-up strike are accurate, it implicates serious legal issues.

'This rises to the level of a war crime if it's true,' said Democratic Senator Tim Kaine.

Republican lawmaker Mike Turner emphasized that Congress lacked confirmation regarding the follow-up strike but acknowledged its seriousness if substantiated.

The comments follow the Republican-led Senate Armed Services Committee's announcement on Friday that they planned to conduct 'vigorous oversight' on the strikes.

Hegseth refuted the claims, asserting that the operations were lawful under US and international law. President Trump indicated that the administration would review the situation, expressing disapproval of a second strike.

The Venezuelan National Assembly also condemned the boat strikes, promising a thorough investigation into the accusation of a second attack.

This situation showcases the rising tensions not only between the US and Venezuela but also raises crucial questions about military actions and legal boundaries in international waters.