Six cases of mistaken identity were behind the pre-Christmas grounding of six Air France (search) flights between Paris and Los Angeles over terrorism fears, a police official said Friday.

The names of six passengers sounded similar to those of terrorist suspects provided by the FBI, prompting the French government to ground the planes, the official said on condition of anonymity.

Interior Minister Nicolas Sarkozy refrained from criticizing the United States when asked whether American intelligence had provided erroneous information that led to the cancellations.

"I don't think there are systematic errors. We are exchanging passenger lists," Sarkozy said. "There are problems of people who share the same name.

"It's a period of tension and a period of risk," he said on a tour of security at Charles de Gaulle airport (search). "I prefer the principle of precaution."

Pierre Debue, director of the French border police, said U.S. officials have asked France to check out a few suspicious names on passenger lists nearly every day since Christmas Eve.

One turned out to be a 5-year-old child, and another was a prominent Egyptian scientist, he said. The Wall Street Journal said two other suspected "terrorists" turned out to be an elderly Chinese woman and a Welsh insurance agent.

French police officials, speaking on condition of anonymity, said errors in spelling and transcribing Arabic names played a role.

That usually poses fewer problems for French intelligence, Debue said, because France is accustomed to dealing with Arabic names because of its high immigrant population from North Africa.

Following the flight cancellations, French judicial officials said that U.S. intelligence officials told their French counterparts that members of the Al Qaeda (search) terrorist network may try to board the planes over Christmas.

But careful scrutiny of passenger manifests and the brief questioning of seven passengers failed to turn up evidence that a suicide hijacking was in the works.

French authorities went ahead and authorized a flight several days ago "that American authorities didn't particularly want," Deputy Transport Minister Dominique Bussereau said Friday.

"We thought that all security measures had been taken, that the verifications of passengers had been such that this flight had every reason to fly," he said on Europe-1 radio. He did not identify the flight.

Meanwhile, two Air France flights, on Tuesday and Wednesday, were joined by F-16 fighter jets as they approached Los Angeles for landing, according to the Washington Post and the Los Angeles Times.

Bussereau said French jet fighters also sometimes escort passenger aircraft. However, the interior minister said that such a scenario might occur "someday." Spokesmen at the ministries did not return calls seeking clarification.

Sarkozy said France added 176 extra police at Paris airports in 2003, and said it will test a biometric screening system early this year. After review, officials also revoked about 15 percent of security badges at the capital's airports, he said, without elaborating.

France has largely proved a cooperative partner with the United States, which fears that a commercial aircraft could again be used as a missile in a terrorist attack, as was the case Sept. 11, 2001.

Special agents trained in rapid intervention have been flying undercover on some French flights to the United States even before Washington asked this week that foreign airlines put armed air marshals on certain flights.