US forecasters warned Wednesday that former tropical storm Leslie had swollen to become hurricane, the sixth of the Atlantic season.

The National Hurricane Center said the storm, currently about 465 miles (750 kilometers) southeast of Bermuda, had "strengthened into a hurricane" with sustained winds of 75 miles (120 kilometers) per hour.

The British island territory of Bermuda, home to around 70,000 people, lay square in the middle of the storm's projected path, but otherwise it was expected to remain well clear of the US mainland.

The last hurricane, Isaac, battered Haiti and Cuba and drenched the southern US state of Louisiana last week, leaving more than 20 dead in its wake, seven years after New Orleans was devastated by Hurricane Katrina.