The biggest oil spill in history has reached the world's largest offshore oil field, sparking a furious fight to protect area oil production facilities and the environment, reports said.

A Saudi government wildlife commission issued a report Wednesday saying last month's spill of an estimated 7 million barrels - or 294 million gallons - of oil in the Persian Gulf has caused "heavy losses" among several marine species.The spill created a huge slick that has been creeping along the gulf and is now said to have reached the oil field in Safaniya along Saudi Arabia's northeast coastline.

The oil field is operated by the giant firm Saudi Aramco, which operates water desalinization plants in both Safaniya and Tanajib and has hired hundreds of workers to place booms around the intake pipes for the facilities.

Desalinization removes salt from water. Fresh water is needed to process the crude that comes from oil wells.

Segundo Fernandez, operating manager of the desalinization plant at Tanajib, said if the oil enters the desalinization plants at either Tanajib or Safaniya, "it would basically shut down the water plant because it would foul their filtering system."

The slick Wednesday was about three days away from the Aramco oil complex at Tanajib, some 10 miles to the south of Safaniya.

A report Wednesday by the Saudi National Commission for Wildlife Conservation and Development said its survey of the affected areas found "heavy losses in wildlife species, such as the marine turtles, cormorants, grebes, gulls and waders."

It listed threatened species as green turtles, the hawksbill turtle, dugong, whales, dolphins and porpoises and other wintering birds such as the flamingo.