MIAMI - The National Hurricane Center in Miami says tropical storm Gustav has formed in the central Caribbean, and is heading for the Dominican Republic and Haiti.

Reports from a U.S. air force Hurricane Hunter aircraft indicate that the storm has maximum winds near 96 kilometres per hour.

Earlier in the day, when the storm was a tropical depression, forecasters said the centre of the storm would be moving near or over southwestern Haiti on Tuesday.

The Dominican Republic and Haiti both issued tropical storm warnings for the southern and western parts of the island shared by the two countries.