A year after a passenger failed to blow up an airliner with a shoe bomb, the FBI is warning that terrorists remain interested in carrying out such an attack and that winter coats and shoes could be used to conceal explosives.

In an advisory sent out Monday night to law enforcement nationwide, the FBI said it had no information of any specific threats or plots for a holiday terrorist bombing, according to officials familiar with the advisory.

But the FBI advisory said U.S. authorities continue to receive intelligence that terrorists remain interested in a shoe bomb attack like the one Richard Reid was prevented from carrying out a year ago this week, the officials said, speaking only on condition of anonymity.

Reid, a British citizen, was overpowered by passengers and crew aboard an American Airlines jet on Dec. 22, 2001, after he unsuccessfully sought to light the fuse of an explosive hidden in his shoes. The Paris-to-Miami flight was diverted to Boston, where Reid was taken into custody.

Reid, 29, has since pleaded guilty to trying to blow up the flight. A convert to Islam, Reid has acknowledged in court that he is a member of Al Qaeda and pledged his support to Usama bin Laden. He faces between 60 years and life in prison when sentenced Jan. 8.

The officials told The Associated Press the FBI's advisory Monday was timed to remind law enforcement of the one-year anniversary of Reid's failed attack and to urge vigilance in warding off such attempts in the future.

The officials said the warning suggested that winter jackets, shoes and other items of clothing could be used by terrorists to conceal explosives.

"The advisory was designed to simply remind law enforcement that terrorists often like anniversaries and that they also remain interested in shoe bombs as a possible form of attack," one senior law enforcement official said. "But it was not based on a specific threat."

Even when it does not have specific information about terrorist plots, the FBI has been trying to send local law enforcement agencies nationwide advisories every seven to 10 days highlighting the most recent analysis of intelligence to keep officials focused on possible threats and to identify potential "soft targets" that might be selected by terrorists, the officials said.

Beyond the one-year anniversary and Reid's impending sentencing in a federal courthouse in Boston, there have been other recent developments in the shoe bomber case.

French authorities late last month detained seven suspected Islamic militants with possible ties to Reid.

Anti-terrorism judges authorized the pre-dawn arrests of six Algerians and Pakistanis in Paris' suburbs, including one imam of a mosque. A seventh suspect who once ran a Paris prayer hall was picked up on Reunion island, a French territory in the Indian Ocean, officials said.

FBI officials have said they suspected Reid received help in creating the shoe bomb and continue to look for possible accomplices. Among the evidence authorities are pursuing is an unidentified hair and a palm print found on the explosives inside Reid's shoes.