New Orleans Mayor Roy Nagin has ordered the mandatory evacuation of his city, as Gustav surges toward the U.S. Gulf Coast as a dangerous Category 5 hurricane.

The order will become mandatory at 8 a.m. Sunday for neighbourhoods in the west bank.

Louisiana authorities say they are well-prepared for Gustav, and have learned from hurricane Katrina's destructive path through the state in 2005.

"We've been extremely busy," Veronica Mosgrove, spokesperson for the Louisiana Homeland Security and Emergency Preparedness Office, told CTV Newsnet from Baton Rouge on Saturday.

"What makes this situation different from what happened three years ago is that the state has pre-positioned commodities and resources, like food and water, ready to roll once this thing hits."

Thousands of National Guard members have been called to service in New Orleans. The city was devastated by Katrina, and it became a focal point for critics who said the state and federal governments had failed to adequately protect residents -- especially those living in the poorest neighbourhoods.

"Katrina was a real awakening for many of us," said Mosgrove. "It's been quiet for a few years, and we're hoping people haven't become apathetic."

Louisiana has contracted more than 700 buses to transfer people out of harm's way, taking residents to about 30,000 shelters in the state, at the cost of US$7 million.

Many people living in New Orleans have already chosen to board those buses. On Saturday, a line of people nearly two kilometres in length twisted its way through the parking lot at Union Passenger Terminal.

Joseph Jones Jr., 61, waited in line for more than two hours. He told The Associated Press that when Katrina threatened the city, he got stuck on a highway overpass.

"I don't like it. Going someplace you don't know, people you don't know," Jones said. "And then when you come back, is your house going to be OK?"

U.S. President George Bush has already offered the support of the federal government when Gustav strikes the Gulf Coast.

Gustav has killed at least 81 people in the Caribbean and continues to grow in intensity.

With files from The Associated Press