A US military attack on a ship allegedly carrying drugs from Venezuela left two survivors who have reportedly been captured by US forces and are being held aboard a Navy ship.

The attack, which took place on Thursday, is at least the sixth US strike on Venezuelan ships in recent weeks. It was the first time that survivors have been reported.

President Donald Trump confirmed the attack on Friday, calling the vessel a "drug-carrying submarine".

Trump has ramped up threats against Venezuela's leadership over claims that the country is sending drugs to the US. Venezuela President Nicolás Maduro has accused Trump of trying to make the South American nation "an American colony".

The two survivors of the attack were rescued by a US military helicopter, and were then shuttled onto a US warship in the Caribbean, unnamed US officials have told US media.