US President Donald Trump called Colombian President Gustavo Petro an "illegal drug leader" on Sunday and said payments to the South American nation would cease, while Defense Secretary Pete Hegseth said US forces had attacked a vessel associated with a Colombian rebel group.

Trump's comments marked a new low in relations between Bogota and Washington, which have frayed since Trump returned to office in January and since his administration launched a series of strikes on vessels allegedly transporting drugs in the Caribbean.

The US president said on social media that the United States would stop large-scale payments and subsidies to Colombia and Republican Senator Lindsey Graham, a close ally, said Trump will soon announce "major tariffs" on the country.

Colombia currently pays 10 percent tariffs on most imports to the United States, the baseline level Trump has imposed on many countries.

Hegseth wrote on X that the Pentagon had destroyed a vessel and killed three people on Friday "in the USSOUTHCOM area of responsibility," which includes the Caribbean.

He said the ship was affiliated with the leftist rebel group National Liberation Army and was involved in illicit narcotics smuggling, without offering evidence to back the claim.

"President Gustavo Petro, of Colombia, is an illegal drug leader strongly encouraging the massive production of drugs, in big and small fields, all over Colombia," Trump wrote on Truth Social.

"The purpose of this drug production is the sale of massive amounts of product into the United States, causing death, destruction, and havoc," Trump wrote.

Reuters could not immediately establish which payments Trump was referring to.

Colombia was once among the largest recipients of US aid in the Western Hemisphere, but the flow of money was suddenly curtailed this year by the shuttering of USAID, the US government's humanitarian assistance arm.

Colombia's Foreign Ministry condemned Trump's remarks as offensive and a direct threat to its sovereignty, and vowed to seek international support in defence of Petro and the country's autonomy.

"These accusations represent an extremely serious act and undermine the dignity of the president of Colombians," it said in a statement.

Last month, the United States revoked Petro's visa after he joined a pro-Palestinian demonstration in New York and urged US soldiers to disobey Trump's orders.

The US administration's deadly strikes on boats in the Caribbean have also outraged Colombians. Many legal experts and human rights activists have condemned the extraordinary series of military actions, with Amnesty International describing it as murder on the high seas.

Earlier this month, Petro said one of the strikes hit a Colombian vessel, an allegation the Trump administration denied.

Petro condemned the most recent bombing, saying the boat belonged to a "humble family", not the National Liberation Army.

He also hit back at Trump's remarks.

"Mr. Trump, Colombia has never been rude to the United States... but you are rude and ignorant to Colombia," Petro responded on X.

"Since I am not a businessman, I am even less a drug trafficker. There is no greed in my heart." (Reuters)