French officials have canceled at least six Air France flights between Paris and Los Angeles because of unspecified security concerns. Los Angeles international airport is at its highest security level since the 2001 terror attacks on the East Coast.

French officials say the canceled flights, which originated in both Paris and Los Angeles, had been scheduled for Wednesday and Thursday. Officials of the U.S. Department of Homeland Security had recently met with French officials, and a French government statement said the flights were canceled based on information gathered in the context of the "fight against terrorism."

Neither French nor U.S. officials have revealed the nature of the threat.

Los Angeles has one of the world's busiest airports. It was the target of a foiled bomb plot by an Algerian national around New Year's Day 2000.

The cancellations came almost two years to the day after the arrest of so-called "shoe bomber" Richard Reid, a British citizen who failed to detonate explosives in his shoe on a flight from Paris to Miami.

After the terrorist attacks following near New York and Washington, the Los Angeles airport was closed for two days, and private vehicles were barred from the road linking the terminals for another two months.

This week, the U.S. Department of Homeland Security raised the nation's terror alert level from "elevated" to "high," based on what it said was an increase in the volume of threat-related intelligence reports.

Following that alert, stringent security measures were again put into place at the Los Angeles airport. They are causing delays, but this traveler doesn't mind. "It's necessary in order to protect everybody who's traveling. I mean, it's obviously annoying and you have to account for the time, but I think it's appropriate."

More than 2.5 million passengers are expected to pass through Los Angeles International Airport over the Christmas and New Year holidays.