Amsterdam-based Israeli airport security firm ICTS International (Nasdaq:ICTS) had operated the Boston airport checkpoint from which one of the flights that crashed into New York's World Trade Center on September 11 set out, the company said.

ICTS is now concerned about the possibility of lawsuits, say sources close to the company, although the fact that it ran the checkpoint does not necessarily indicate any malfunctioning on its part.

The company, based in the Netherlands and controlled by Israeli shareholders, among others, provides security services at 48 airports in the United States through its subsidiary Huntleigh USA. United Airlines is one of ICTS's customers.

The company's chief executive, Lior Zouker, today refused to comment to questions from TheMarker.com. In a press release, the company revealed that Huntleigh had operated a checkpoint from which an aircraft later commandeered by terrorists departed.

American Airlines Flight 11 and United Flight 175 both departed from Boston's Logan International Airport early September 11. Both were crashed by hijackers into New York's World Trade Center.

Another American Airlines flight, 77, that had taken off from Dulles was crashed into the Pentagon, and United Flight 93 crashed in Pennsylvania after reportedly being recaptured by passengers, who failed to restabilize it.

Federal Aviation Administration investigators are looking at whether box-cutting knives, such as the kind used in the hijackings two weeks ago, may have been planted the jets by anyone other than passengers. Meanwhile, in a radical departure from current practice, the U.S. Air Line Pilots Association is calling to allow pilots to fly armed.

ICTS stock soared 100% to $9.75 since trade on Wall Street resumed after the attacks on the U.S.

The company's revenues jumped 30% in the second quarter of 2001 to $47 million, while its net profit sank from $840,000 in the parallel quarter of 2000 to $10,000.