New Orleans: Hurricane Gustav sent strong winds and lashing rains into New Orleans on Monday, but weakened as it was expected to move ashore to the west.

Gustav weakened to a Category 2 hurricane shortly before making landfall, although it was already pounding Louisiana's coastal areas with torrential rain and strong winds.

Nearly two million people fled the Gulf Coast in one of the biggest evacuations in US history and only 10,000 were believed to have remained in New Orleans.

Police and several thousand national guard troops patrolled the empty city, sometimes in convoys of Humvees, as a curfew went into effect in a bid to prevent looting.

The US National Hurricane Center said Gustav was still likely toss up "an extremely dangerous storm surge" of up to 4.3 metres that could test the holding power of rebuilt levees that failed during Hurricane Katrina.

Gustave was expected to swamp parts of Louisiana, Mississippi, Arkansas and Texas. Isolated tornadoes were also possible.

Hurricane Gustav began to lash southern Louisiana on Monday after a destructive march across the Caribbean where it smashed thousands of homes.

In Cuba, Gustav destroyed 86,000 homes, toppled trees and telephone poles and washed out roads, but no deaths were reported Sunday.

Gustav earlier killed 94 people by triggering floods and landslides in Haiti, the Dominican Republic and Jamaica.