The US military says it struck two boats it alleges were carrying drugs on Wednesday, killing five people on board.

US Southern Command did not say where it had carried out the latest strikes but US forces have been targeting vessels they suspect of smuggling narcotics through the Caribbean and eastern Pacific for the past three months.

Wednesday’s strike came a day after the US targeted what it said were “three narco-trafficking vessels travelling as a convoy”, killing at least three people.

The Trump administration has cast its operations as a non-international armed conflict with the alleged traffickers but legal experts say they could be in violation of the laws governing such conflict.

In total, there have been more than 30 strikes on vessels as part of the Trump administration’s “war on drugs” with more than 110 people killed since the US carried out its first attack on a boat in international waters on 2 September.

That first attack has come under particular scrutiny from lawmakers in Washington since it emerged that US forces struck the targeted boat twice.

Two people who had survived the first strike and were clinging to the hull of their boat were killed in the second.

Some lawmakers expressed concern that the “double-tap” strike breached the rules of engagement.

In its post announcing the strike on a convoy of three boats carried out on 30 December, US Southern Command said that there had been a number of survivors, without specifying how many.

It said that “the remaining narco-terrorists abandoned the other two vessels, jumping overboard and distancing themselves before follow-on engagements sank their respective vessels”.

It added that the US Coast Guard had been “immediately notified” to search for the survivors.

Reuters news agency reports that it was told by a US official who asked to remain anonymous that eight survivors were being searched for.

It is not yet clear if any of them have been found.

The US has provided no evidence that the boats it has targeted are carrying drugs but in its most recent post, Southern Command again insisted that “intelligence confirmed the vessels were transiting along known narco-trafficking routes and engaged in narco-trafficking”.