The US has placed sanctions on Colombia's left-wing president, Gustavo Petro, accusing him of failing to curb drug trafficking.

President Petro has allowed drug cartels to flourish and refused to stop this activity, US Treasury Secretary Scott Bessent said in a statement.

Sanctions have also been imposed on Colombia's Interior Minister Armando Benedetti, as well as Petro's wife and eldest son. They include barring them from accessing assets and properties they may have in the US.

Colombia was once a close ally of Washington's war on drugs, receiving hundreds of millions of dollars annually in military assistance. But Petro and Trump have clashed frequently since Trump's return to power.

Bessent said that since Petro, a former guerrilla, came to power, cocaine production in Colombia has exploded to the highest rate in decades, flooding the United States and poisoning Americans. He added that Trump was taking strong action and would not tolerate drug trafficking into the US.

The Treasury stated that Colombia was the world's top exporter of cocaine, which poses a significant drug threat to the US.

In a separate statement, the state department said it would not certify Colombia's counter-narcotics efforts.

Petro denied the accusations, claiming he had fought drug trafficking for decades and had assisted the US in reducing its cocaine consumption. He described the situation as a complete paradox - but not one step back, and never on our knees.

In recent weeks, the US military has intensified operations in the southern Caribbean, targeting vessels allegedly transporting drugs. Last week, Trump announced the suspension of payments and subsidies to Colombia after Petro characterized US airstrikes on suspected drug vessels as an act of tyranny, asserting that US actions were undermining Colombian sovereignty.

Imposing sanctions on a head of state is rare but not unprecedented; leaders of countries including Russia, North Korea, and Venezuela have faced similar actions.