Hijackers who seized a Cuban ferry boat with 50 people aboard have demanded fuel to get to the United States.
They are threatening to throw hostages overboard as the boat drifted in choppy international waters off Cuba.
In the second hijacking in two days and the third in three weeks, Cubans armed with three handguns and a knife took control of a Havana Bay ferry yesterday and sailed out into the Florida Straits toward the United States.
The ferry ran out of fuel 30 miles off Cuba and is adrift in high seas, the Cuban government said.
The sudden spate of hijackings comes as tensions between the United States and Cuba have worsened due to US support for dissidents on the communist-run island. When tensions have risen in the past, Cubans have seized the opportunity to try to leave.
Moving to dissuade Cubans from resorting to illegal means to cross the Florida Straits, the US mission in Havana said Cubans hijacking planes would be severely punished and ineligible for residence in the United States.
A US official said in a statement read out on Cuban national television that the hijackers of two Cuban planes in the last two weeks were being tried in Florida and Cubans committing similar crimes should expect the same fate.
He urged Cubans who wanted to emigrate to apply for visas.
The US government said was Cuba's responsibility to deal with the hijacked boat.