Highly toxic styrene has leaked from an Italian tanker that has sunk off the France's Atlantic Coast and a "strong odour" of chemicals has been detected over the site where the boat went down, according to French officials.

Highly toxic styrene has leaked from an Italian tanker that has sunk off the France's Atlantic Coast and a "strong odour" of chemicals has been detected over the site where the boat went down, according to French officials.

French maritime police said an urgent appeal had been launched warning boats to stay at least three miles from the site where the "Ievoli Sun" tanker sank Tuesday.

Scientists set to sea Wednesday on a French military vessel to take sea and air samples to determine if an Italian cargo ship carrying dangerous chemicals that has sunk off the Channel Islands has leaked dangerous chemicals.

The sinking of the "Ievoli Sun" tanker, which is carrying 6,000 metric tons of dangerous chemical products, has raised alarm at the highest political levels in France, coming less than one year after an aging Maltese-registered tanker, the "Erika" sank, polluting large stretches of France's picturesque Atlantic coast.

French President Jacques Chirac traveled Wednesday morning to the French port of Cherbourg in Brittany for an assessment of the risks of pollution and to inspect the efforts to raise the vessel and isolate its cargo.

The "Ievoli Sun" sank Tuesday northwest of Alderney, one of the Channel Islands, and anti-pollution teams searched the surrounding water for potential spills, maritime officials said. The tanker sent out distress signals Monday as gale-force winds lashed France's Atlantic coast. A helicopter evacuated the 14 members of the crew.

A rescue tug was sent to help the stricken vessel, but it could not make port before sinking.

The tanker was carrying mostly styrene, used to make plastics, rubber and resins. Other products on board included isopropyl, or rubbing alcohol, and methyl ethyl ketone, often used as a solvent.

Saying the incident poses a "serious threat to the environment," French Environmental Minister Dominque Voynet condemned "the irresponsibility of those who did not anticipate the expectations of society regarding maritime safety."

Environmental groups warned that the chemicals - especially styrene - could cause serious ecological problems if they leaked out of the ship. Styrene is highly toxic and causes cancer in laboratory animals.

French maritime police said the styrene was mixed with fuel from the tanker. Adm. Laurent Merer said it was not clear what had caused the foul smell in the area where the boat sank.

"There is a potential for a serious marine pollution incident here," said Paul Johnson, a Greenpeace International scientist based at Exeter University in southwest England. "The real question is how much is going to leak out."

After visiting the site, French Transportation Minister Jean-Claude Gayssot told the National Assembly in Paris that traces of pollution had been detected in the area where the tanker sank.

Shell Chemicals, which chartered the ship, said the styrene on board would not damage the environment. In case of a spill, the company said in a statement, the styrene would float to the surface, evaporating in a matter of hours.

But Voynet disputed that, saying at a news conference in Cherbourg that styrene is "potentially dangerous ... if it escapes from the boat."

The ship is about 60 to 80 meters (198 to 264 feet) below the surface.

Fierce gales of up to 150 kilometers per hour (93 mph) swept much of northern France on Monday, killing four people and seriously disrupting rail, air and sea travel.

Chirac said he hoped the European Union would quickly adopt French proposals for stricter maritime measures.