Chilean frogmen worked to stop oil from leaking from a partially submerged ship off Antarctica, authorities said, and a report Wednesday said thousands of polar seabirds have already died near the spreading slick.

Crewmen from the Chilean cutter Yelcho on Tuesday encircled the nearly sunken Argentina vessel Bahia Paraiso with floating booms designed to contain any further leakage, said a navy communique released in Santiago.New Zealand Press Association Wednesday reported that thousands of baby Polar Skua gulls had died because their parents were unable to find food.

The predatory birds also can freeze to death if the oil disrupts their natural insulation or be poisoned if they swallow oil while preening themselves or eat contaminated prey.

The news agency, citing unidentified scientists at the nearby U.S. Palmer Station on the Antarctic Peninsula, said the oil slick has surrounded penguin rookeries near the wrecked ship.

An operator reached by telephone at the research station referred all inquiries to the Washington-based National Science Foundation, which oversees the base 590 miles from the tip of South America.

The Argentine research and supply ship grounded on shoals Jan. 28.

The ship holds about 800 tons of fuel, including diesel oil in bulk and aviation fuel in steel drums. The National Science Foundation says oil is leaking slowly from the ship, which gradually sank in the shallow waters. Only a section of its superstructure remains above the surface.

Foundation officials said Tuesday that a slick nearly 500 feet wide and two miles long was trailing away from the vessel toward the south, threatening the frozen continent's fragile and unspoiled environment.