Wildlife dying because of oil spill: WWF

Oil began escaping on August 21 from a well at the Montara oilfield, more than 200km off Western Australia's north-west coast.

Three attempts by the company which operates the oilfield, the Thai-based PTTEP Australasia, to plug the leaking well with heavy mud have failed. Another attempt will be made on Friday.

World Wildlife Fund (WWF) conservation director Dr Gilly Llewellyn said dolphins, migratory sea birds, sea snakes and marine turtles have been found in slick-affected area during a recent survey.

The survey report, released on Friday, painted a grim picture of a rich marine community under threat of toxicity from the Montara oil leak.

"We recorded hundreds of dolphins and sea birds in the oil slick area, as well as sea snakes and threatened hawksbill and flatback turtles," Dr Llewellyn said.

The reality was in stark contrast to comments made this week by the Australian Petroleum Production and Exploration Association that the survey found no evidence of harm to marine life."

The WWF expedition recorded 17 species of seabird, four species of cetacean and five marine reptiles, including two marine turtle species.

On Wednesday PTTEP reported 25 birds had been affected by oil and 16 of those birds had died.

The company said there were no reports of any whales or dolphins in trouble and tests undertaken on fish specimens to date showed no contamination by oil. "Clearly, wildlife is dying and hundreds if not thousands of dolphins, seabirds and sea-snakes are being exposed to toxic oil," Dr Llewellyn said.

"The critical issue is the long term impact of this slick on a rich marine ecosystem, taking into consideration the magnitude, extent and duration of the event."

Oil could be a slow and silent killer, Dr Llewellyn said. "Impacts from the Exxon Valdez disaster are still being seen 20 years later, so we can expect this environmental disaster will continue to unfold for years to come," she said.

On Wednesday, the Greens said a senate estimates hearing had revealed the amount of oil spilling from the well was far greater than PTTEP estimates, based on Geoscience Australia data.