Cuba's civil defense office issued a warning for the provinces of Guantanamo, Santiago de Cuba, Granma, Holguin and Las Tunas, while warnging the rest of the country of 11 million to stay informed of the storm's track.

Cuba's Weather Service agreed with the forecast of the US National Hurricane Center in Miami calling for Dennis to strengthen over the course of the day.

"Outer rainbands of Dennis were beginning to spread over southern coast of Hispaniola," the island shared by Haiti in the west and the Dominican Republic in the east, just east of Cuba, the US center said at 1800 GMT.

"A hurricane warning is in effect for Jamaica and for the southwestern peninsula of Haiti from the Dominican Republic border westward," it added.

"A hurricane watch is in effect for the Cayman islands and for central and eastern cuba," it added.

Packing maximum sustained winds are near 70 mph (110 km/hr) with higher gusts, the center of tropical storm dennis was about 350 miles (565 km) east-southeast of Kingston, and the storm was moving toward the west-northwest near 14 mph (25 km/hr), the US center said.

"Some strengthening is forecast during the next 24 hours" and "this general motion is expected to continue during the next 24 hours. On this track, Dennis will be near Jamaica early Thursday," it added.

Dennis' heavy rains, particularly in mountainous areas, "could produce life-threatening flash floods and mud slides," the US center warned.