PARIS — Investigators have discovered strong signs that an explosion that damaged a French oil tanker off the coast of Yemen this week and killed one sailor resulted from an attack by terrorists using a small boat, French authorities said Thursday.
U.S. intelligence officials in Washington concurred, saying they believe that the attack Sunday on the French supertanker Limburg was part of a broad new terrorist campaign against American and allied interests in the Middle East that may involve Al Qaeda.
Despite initial claims by Yemeni officials that the explosion was accidental, French investigators working with U.S. and Yemeni counterparts Thursday aboard the Limburg found pieces of wood, metal and other materials believed to be debris from another boat, according to French law enforcement and diplomatic officials.
The physical evidence reinforces the account of a sailor who said he saw a small vessel about to ram the tanker Sunday morning just before the explosion, which caused a massive fire and spilled about 90,000 barrels of oil.
"The preliminary results of the inquiry conducted by French, Yemeni and American investigators lead us to believe that the explosion suffered by the French oil tanker Limburg was due to an attack," the French Foreign Ministry said in a statement Thursday night. "The course of the inquiry will enable the verification of these first results and determine the exact causes of this explosion."
The clues were found as investigators scoured the tanker's hold in the area of a gaping hole near the waterline. Experts from France's leading anti-terrorism agency, the DST, determined that the materials were consistent with a small boat and suggested a seagoing attack with explosives, authorities said.
"They found pieces of wood and of other materials that apparently come from a small boat," a French law enforcement official said. "This was an intentional act. This looks more and more like a terrorist attack."
The investigators also found metallic debris at the blast site that they suspect came from such a craft, another French official said.
The U.S. naval investigators confirmed that pieces of a small boat were inside the Limburg, according to a U.S. official who spoke on condition of anonymity. The tanker's hull was bent inward, according to the official--further evidence of an attack.
"There are clearly signs of a terrorist attack," said a U.S. intelligence official familiar with the investigation.
France put its diplomatic facilities in the Middle East and other trouble spots on alert Thursday and said the government would provide additional protection for French ships.
The explosion in the Gulf of Aden appears to be part of a recent wave of attacks and heightened activity around the world attributed to the Al Qaeda terrorist network and its sympathizers, according to French and U.S. authorities.
The method and location recall a bombing two years ago that killed 17 sailors aboard the U.S. destroyer Cole, which was struck by an explosives-laden boat steered by suicide terrorists off the coast of Yemen. U.S. officials blamed Al Qaeda for that attack.
The Limburg incident came only a week before the second anniversary of the assault on the Cole. A senior French law enforcement official said that although it was too early to blame Al Qaeda, such symbolic timing has been a signature of the group.
The U.S. official said the blast on the Limburg has all the hallmarks of an Al Qaeda operation.
"It's harder for just one or two individuals to conduct an attack like that; it takes a lot more coordination and effort," the official said. "It does seem to be pointing to an attack like that on the Cole."
If that is true, the bombing could confirm recent grim portents. European and U.S. counter-terrorism experts have warned for months that oil tankers were prime targets of terrorists bent on economic disruption and mayhem. There was a threat of attacks on French interests in a recently aired tape of the voice of fugitive Ayman Zawahiri, the alleged right-hand man of Osama bin Laden. And recent intelligence intercepts described by U.S. justice officials indicated that Al Qaeda was gearing up for more terrorist acts.
Moreover, suspected Islamic extremists killed a Marine on Tuesday during a military exercise in Kuwait, though the U.S. official said Thursday that it is not clear whether that shooting might be tied to the explosion in Yemen or directly to Al Qaeda.
Yemeni officials spent the first days after the Limburg blast denying allegations of terrorism, as they did after the October 2000 attack on the Cole. But they backtracked Thursday, saying terrorism was a possibility.
A Yemeni terrorist group linked to Al Qaeda has claimed responsibility for the Limburg blast. French authorities will consider that claim seriously, but they have no information yet with which to evaluate its credibility, a French diplomat said.