LA CORUNA, Spain -- The sunken prestige tanker is leaking nearly 125 tons of oil per day into the waters off northwest Spain and could take up to 39 months to finish spewing its cargo, a scientific committee estimated on Tuesday.

Meanwhile changing winds threatened to once again drive some of the oil onto the Galicia region's sludge-stained beaches, according to local government sources.

The leaking oil "takes about a day to arrive at the surface" and is escaping through 14 cracks and gashes in the prestige's single-hulled holding tanks, Mariano Rajoy, Spain's deputy prime minister, said quoting the scientists' estimates.

Previous reports had put the number of gashes at nine and 15.

It should take between five and 39 months for the tanker to stop leaking oil, commission head Emilio Lora-Tamayo said, adding that the cracks and gashes do not seem to be growing larger.

Two of the prestige's tanks -- the central tank and a side stern one -- are leaking, Lora-Tamayo said.

The committee was put together by Spain to examine observations of the prestige wreck made by a French submersible.

A change to westerly winds Tuesday afternoon threatened to push oil slicks, both on and below the surface, toward Galicia's ecologically-sensitive beaches, the Galician regional government reported on its website.

One slick spotted on the surface above the wreck measured more than 1,000 square kilometers (386 square miles) and was estimated to contain 31 tons of oil.

Several smaller slicks are floating 85 kilometers (47 miles) from the northern Galician coast, according to latest government bulletins.

Since Friday, easterly and northeasterly winds had given some stretches of Spain's northwest coast a reprieve, carrying the oil into the open sea.

Now slicks have again turned toward shore, the government site said.

"We are on tenterhooks because with the winds, the threat can return," said Jose Mos, head of a local fishermen's association.

Despite strong swells, local fishermen, reinforced by thousands of Spanish troops, have been cleaning up small oil slicks along the coast full of inlets.

Thousands of volunteers joined the cleanup effort this past weekend, mopping up sludge.

Meanwhile an international fleet of anti-pollution vessels has sucked up large drifts of oil in the open seas.

Stretches of the Galician coast, an important fishing and mussel-producing region, have twice in the past month been inundated with the black muck washing ashore.

The prestige broke in two and sank on November 19, 270 kilometers (170 miles) off Spain's northwest coast. Its bow and stern lie 3.7 kilometers (2.3 miles) apart, some 3,500 meters (11,500 feet) down on the Atlantic seabed.

The tanker had leaked oil for six days and was estimated to have spilled 10,000 tons of its 77,000-ton cargo before sinking.

Since then, it has leaked between 17,000 - 20,000 tons more, the scientific committee estimated, adding that about 56,000 tons remain in its tanks.

The French mini submarine nautile has made five dives to the tanker and will continue its observations during its current eight-day trip to the site.

The seepage from the seabed is particularly worrying to Spanish authorities as it could cause continuing pollution in the area for months to come.

Galicia is more dependent on its fishing industry than any other region of the 15-nation European Union, with more than 120,000 jobs.

In addition to Galicia, beaches in the Spanish provinces of Asturias, Cantabria and the Basque country have been polluted. To the south, small slicks were beginning to wash ashore on Portuguese coasts.

The prestige, owned by a Liberian-registered company and flying the Bahamas flag of convenience, was operated by a Greek company.