Hurricane Ike has weakened into a Category 2 storm after roaring ashore in north-east Cuba, but forecasters say it could regain intensity as it spins toward the US oil hub in the Gulf of Mexico and possibly New Orleans.

Ike pounded north-east Cuba with 165 kilometres per hour winds, torrential rains and massive waves, and it could slow further to a Category 1 storm on the five-step Saffir-Simpson intensity scale as it runs the 1,125 kilometre island, the US National Hurricane Centre said.

Cuba's state-run television showed angry waves slamming into the sea wall and surging as high as nearby five-story apartment buildings before flooding the streets of the city of Baracoa near the eastern tip of the communist-ruled island.