Tropical storm Nate has strengthened into a category one hurricane and is speeding towards the United States after killing at least 22 people in Central America, the US National Hurricane Center said on Saturday.

The hurricane has sustained winds of 75 mph and is located 495 miles south of the mouth of the Mississippi River, in the southern Gulf of Mexico, Sky News channel reported.

New Orleans Mayor Mitch Landrieu ordered a mandatory evacuation of the Venetian Isles, Lake Catherine and Irish Bayou areas of the city after having already declared a state of emergency Thursday.

"Residents in these areas should heed any evacuation instructions given by local officials," the center said.

The storm is expected to make landfall by Sunday east of New Orleans, which was devastated 12 years ago by Hurricane Katrina. 

It would be the third hurricane, after Harvey and Irma, to hit the US mainland in six weeks.

Source: MENA