OTTAWA - A large Canadian Forces aircraft touched down in New Orleans on Sunday evening, prepared to evacuate "medically vulnerable" individuals from the region threatened by hurricane Gustav.

Defence Minister Peter MacKay said a C-17 plane, carrying a team of 12 medical personnel, arrived in Lakefront, La., around 5:30 p.m. ET and will transport up to 150 people per trip to a safety zone.

"We put the minimal number of Canadian Forces personnel on board to make room for as many people as we possibly could," MacKay said in a telephone interview from Nova Scotia.

"This is, of course, a very fluid situation. We're watching as the storm is upgraded and downgraded in terms of its strength and we're working very, very closely with officials on the ground."

Gustav crossed western Cuba on Saturday and has already killed more than 80 people in the Caribbean.

The hurricane could bring a storm surge of up to six metres to the coast and rainfall totals of up to 38 centimetres.

New Orleans Mayor Ray Nagin, who called the hurricane "the mother of all storms," has issued a mandatory evacuation order, as well as a dusk-to-dawn curfew.

MacKay said Canada's aid efforts come at "minimal cost." They were prompted both by a specific request for the plane from the U.S. NorthCom commander and also by a bilateral agreement signed February 2007 to support each other in times of need, he said.

"This is a purely humanitarian relief effort, in keeping with the best traditions of our country and I would call it a pre-emptive effort at relief and assistance," MacKay said.

The minister added Canada is ready to provide further assistance if necessary, potentially including more aircraft, HMCS St. John's -- already stationed in the region -- or the DART team of engineers, who could provide construction capabilities or water purification.

The Department of Foreign Affairs in Ottawa is advising Canadians against non-essential travel to the northern coast of the Gulf of Mexico, including the city of New Orleans.

A department spokesperson says about 4,000 Canadians are believed to be in Louisiana and up to 30,000 in Texas.

Hurricane Gustav, a Category 3 storm, is expected to hit the area as early as Monday morning. It comes almost exactly three years after hurricane Katrina devastated the area in 2005.