Trump administration has denied involvement after Cuban government says a boat of armed men tried to infiltrate island.

A technical team from the Federal Bureau of Investigation (FBI) has arrived in Cuba to launch an “independent investigation” into a deadly shootout between local border patrol officers and a Florida-tagged speedboat.

The United States embassy in Havana announced the FBI agents’ arrival on Wednesday, following pressure from officials to look into the incident.

On the night of February 25, 10 Cuban nationals tried to enter Cuba by speedboat, armed with nearly 13,000 rounds of ammunition, 13 rifles and 11 pistols, according to authorities in Havana.

Five were killed in the shootout that ensued. The others were wounded and were taken into custody, where they received medical attention, the Cuban government has said.

The US embassy said in a statement the FBI trip to Cuba was part of a “thorough and independent investigation” into the incident.

An embassy official told the Reuters news agency the US would verify Havana’s version of events.

“Consistent with US policy, we do not make decisions in the United States on the basis of what Cuban authorities are saying,” the official said. “We will independently verify the facts and make decisions based solely on US interest, US law, and the protection of US citizens.”

Tensions have soared between the two nations since January, when US President Donald Trump imposed a virtual oil blockade on the island after abducting and imprisoning Venezuelan President Nicolas Maduro, a crucial Cuban benefactor, on January 3.

Cuba said the assailants were Cuban exiles who came from the US with the intent to sow chaos and attack military units.

A Cuban patrol of five border guard members on a nine-metre boat spotted the incoming vessel early that morning, about one nautical mile (equivalent to about 1.85km) off a remote channel on the Caribbean island’s northern coast, some 160km (100 miles) from Marathon, Florida.

The infiltrators fired on the patrol from 185 metres away, striking the captain in the abdomen, Cuba said. Bleeding heavily, the wounded captain remained at the helm and steered towards the enemy vessel, leading to a firefight at a distance of about 20 metres.

Trump’s Secretary of State Marco Rubio said the speedboat incursion was not a US operation and that no US government personnel were involved.