Media reports of a possible problem on the Boeing 747-400 reawakened memories of Sept. 11 when hijackers slammed four airplanes into the World Trade Center, Pentagon and a Pennsylvania field, killing around 3,000 people.

A government official said a screener in London thought one of the passengers aboard the flight looked like someone on a watch list -- a list including photographs of suspicious people that was developed after Sept. 11.

The screener was less clear about the identification when interviewed by authorities.

Nonetheless, FBI officials will meet the plane when it lands in New York to interview that person and verify his identity, law enforcement officials said.

"It may turn out just to be a similar name," one official said. "I would use an abundance of caution."

Another U.S. official familiar with security issues concurred, saying: "It doesn't appear to be anything of concern at this point. There doesn't appear to be anything of concern from a terrorist standpoint."

Canadian Defense Minister Art Eggleton said Canadian fighter jets were monitoring the aircraft but agreed there was no indication it was hijacked. He said U.S. fighters would pick up the airplane once it enters U.S. airspace.

The airplane is due to land in New York around 4:40 p.m.

Rumors of a possible problem on the plane caused financial markets to drop. The blue chip Dow industrial average and broad market gauge S&P 500 shed gains and moved into negative territory.

"There was a story that someone on the terrorist list was on a plane headed to the United States," said Bob Harrington, head of listed trading at UBS Warburg. "The market saw that and it might have caused some concern but later the Dow recovered."