Cuba says it thwarted armed exiles on a Florida-registered speedboat who were trying to infiltrate from the US

A deadly exchange of fire between two boats off the coast of Cuba, killing four and wounding six, has raised already high tensions between Washington and Havana.

Cuba’s government said a US-registered boat was carrying 10 people, most of whom it claimed “have a known history of criminal and violent activity”. The US secretary of state, Marco Rubio, said the US was gathering its own information but called the open sea shootout “highly unusual”.