MIAMI - The U.S. National Hurricane Center in Miami says a new tropical storm has formed northeast of the northern Leeward Islands.

Hanna, the eighth named storm of the Atlantic hurricane season, currently has top sustained winds near 65 kilometres an hour.

Its centre is about 490 kilometres northeast of the northern Leeward Islands and is moving west-northwest near 20 km/h.

Forecasters say Hanna may produce rainfall of between 2.5 and 10 centimetres across parts of the Leewards.