Washington DC - Republican Senator Rand Paul has slammed President Donald Trump's decision to launch military strikes against Venezuelan boats, calling them "extrajudicial killings."

Paul used an appearance on Fox News on Sunday to criticize Trump's violent attacks on Venezuelan fishing boats, which have killed at least 40 people over approximately ten strikes in the Caribbean.

"A briefing is not enough to overcome the constitution," he explained. "The constitution says that when you go to war, Congress has to vote on it, and during a war, then there's a lower rules for engagement, and people do sometimes get killed then without due process."

Paul then pointed out that when the US government has waged a so-called "drug war" in the past, it has always been undertaken by law enforcement and agencies within the US, not by the military.

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"So far, they have alleged that these people are drug dealers – no one has said their names, no one has said what evidence, no one has said whether they're armed, and we've had no evidence presented," he went on.

"So at this point I would call them extrajudicial killings," Paul said. "This is akin to what China does, what Iran does with drug dealers – they summarily execute people without presenting evidence to the public. So it's wrong."

Paul's criticism of Trump is a rare voice from the Republican Party when it comes to denouncing the administration's attacks on the boats, which have been called "murder" by Venezuela's authorities.

It also flies in the face of claims made by Trump on Friday that he "can't imagine" any federal lawmakers having "any problem" with the strikes if he approached Congress for approval.