Rescue workers in South Africa are laying oil-absorbent booms to try to protect a world-renowned nature reserve from a spreading oil slick leaking out of a burning ship.

The specialist equipment backs up earlier attempts to build up sand banks to stop the oil spreading to the Saint Lucia Wetland Park, a World Heritage site.

Wildlife home

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

Conservationists and salvage workers will also try to work out whether the stranded Jolly Rubino freighter - carrying a load of toxic chemicals - can be refloated and towed to sea or if the oil must be pumped out.

The crew abandoned ship after it caught fire on Tuesday, 25 nautical miles (46 kilometres) off the coast, and then drifted towards shore, becoming grounded on rocks less than 200 yards from the wetlands, a key breeding ground and wildlife sanctuary.

Weather hindrance

Changing weather conditions continue to affect the salvage operation.

Work was hampered earlier by gale-force winds and though they have now died down, a change in direction could push the oil slick towards mussel beds, an official for KwaZulu-Natal Wildlife said.

The beached ship was carrying toxic chemicals

Richard Penn Sawers, marine conservation of the Greater Saint Lucia Wetland Park, said: "Today [Sunday], we will hopefully complete laying the oil-absorbent pontoons that will close off the [Umfolozi] estuary completely.

He was quoted by the AFP news agency as saying that a study of 235 birds in the estuary early on Sunday morning had shown the environmentally sensitive area to be free of heavy fuel oil.

Birds are regarded as good indicators of water pollution levels.

"A total of 205 of these birds were of the wading species and they all looked fine," Mr Sawers said.

Disaster declaration

Sipho Magwaza, the director of community services involved with disaster management in the area, said the area surrounding the shipwreck could be declared a disaster area to release funds needed to clean up the tar and debris along the coast.

Captain Nicholas Sloane, salvage master for Smit Salvage, warned that more fuel could leak, or even explode, if the Jolly Rubino broke up.

But decisions on whether to tow the vessel out to sea or pump out the oil on board could only be taken once the fire was out.

By Sunday, the oil that has leaked from the ship's fuel tanks had spread more than six miles (11km) along the coast and some had washed up on beaches.

Richard's Bay Harbour Master 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 Italian-flagged ship had left Durban in South Africa for a journey to Mombasa, Kenya.