Rescue workers will try to refloat a beached freighter leaking oil into the sea near a world-famous nature reserve on South Africa's east coast.

The burning Italian-flagged vessel is in danger of breaking up and spilling more oil near the protected Saint Lucia Wetlands Park.

The vessel is not going to last the two weeks it will take us to control the fire, so we will make an attempt to refloat her

Nicholas Sloane, Salvage Master

Smit Salvage made an unsuccessful bid to put out the fire, which broke out on Tuesday, crippling the vessel and forcing the crew to abandon ship.

But on Monday the fire continued to burn on the freighter, which contains toxic chemicals.

"The vessel is not going to last the two weeks it will take us to control the fire, so we will make an attempt to refloat her," Salvage Master Nicholas Sloane said.

Race against time

Environmentalists are concerned that efforts to pull the boat from the beach could break open the weakened hull, pouring 1,300 tonnes of petrol into the sea.

Rescue workers have so far managed to keep the oil slick away from the protected area, conservationists said.

The public has been warned to stay out of the area

Oil-absorbent booms were placed across the mouth of the Umfolozi river, and bulldozers added man-made dunes to a sand bar that protects the mangrove swamp.

The Jolly Rubino ran aground about 11 kilometres (seven miles) south of the Unesco-recognised wetlands.

The sand around the ship is streaked with heavy fuel oil, and larger patches of oil have been spotted floating near the shore.

Ship cracked

About 400 tonnes of oil are believed to have escaped through a 20 metre (65 foot) crack in the ship's port side.

Crisis management officials held a brief debate over whether to declare the wreck a national disaster, but decided instead to label it a "major incident" after concluding that the situation was not yet out of hand.

Charles Cary, a provincial disaster manager, said the government had moved in to help co-ordinate the operation.

Wildlife home

Saint Lucia is a sanctuary for: Hippos Crocodiles Pelicans Flamingoes Estuarine fish Mangrove forests

"Whether it breaks in the process of pulling it off, or it breaks while sitting there, is the same," he said. "The environment guys are ready for it."

Harbour Master of Richard's Bay, Mike Brophy, said about 70 containers, many of them containing the toxic chemical phenol, had washed overboard.

The 22 crew of the Jolly Rubino were airlifted to safety on Tuesday and the ship's dog was rescued on Friday.

The ship had left Durban in South Africa for a journey to Mombasa, Kenya.