ALSO READAtl least 1.2 million people 'battered' by Hurricane Irma: Red Cross Hurricane Irma most enduring super-storm on record: Weather service 6 dead, 95% properties damaged as Hurricane Irma hits Caribbean island Hurricane Irma: Massive destruction in northern Caribbean islands as 9 die Hurricane Irma batters Caribbean, Florida braces for powerful storm
The eye of the hurricane was expected to pass between the island of Hispaniola, home to Haiti and the Dominican Republic, and the Turks and Caicos Islands early Friday morning, reports Xinhua news agency.
"The core of the hurricane will then move between the north coast of Cuba and the Bahamas," said the statement from Cuba's weather service.
Irma's maximum sustained winds remain at 280 km/h with higher gusts making it a potentially catastrophic tropical cyclone.
The hurricane's outer bands unleashed pounding rain on Cuba's eastern provinces of Guantanamo and Holguin on Thursday night, along with tropical storm force winds and waves that reached 6 to 8 metres high.
Cuba's Civil Defense declared a hurricane warning for all eastern provinces and the central territory of Ciego de Avila, and urged all governments and civilian groups to complete their preparations for the superstorm.
More than 10,000 tourists vacationing in the island have already been evacuated or returned home.
Irma has left a wake of devastation in the Caribbean, killing at least 10 people and damaging homes and other infrastructure in Antigua and Barbuda, Puerto Rico, St. Martin, and the north coast of the Dominican Republic.
It made landfall on Wednesday.
The unusually powerful storm is the strongest ever recorded in the Atlantic.
After grazing northern Cuba, Irma is expected to hit the US state of Florida.