MONTREAL -- A Canadian general who is deputy commander of NORAD has revived the spectre of more than just four commercial airliners targeted for hijacking on Sept. 11.

"We suspect there might have been more than just the four aircraft involved," Lieutenant-General Ken Pennie, the Canadian second-in-command of the North American Aerospace Defence Command, said yesterday.

He said the information stemmed from the fact that suspicious passengers left a grounded plane on Sept. 11, somewhere in North America.

"From our perception, we think our reaction on that day was sufficiently quick that we may well have precluded at least one other hijacking. We may not have. We don't know for sure," Gen. Pennie said.

In the minutes after the attacks, control of the continent's airspace was turned over to NORAD.

Gen. Pennie's comments were made during an impromptu session with reporters before a luncheon speech at Montreal's International Relations Council.

The general would not give more details, saying it was classified information from another source.
"When someone classifies something, someone else can't declassify it," he said.

Gen. Pennie apparently was alluding to a Los Angeles-bound flight grounded at New York's John F. Kennedy airport on Sept. 11, on which three Middle-Eastern passengers angrily demanded that the flight proceed and then were kicked off the plane, vanishing before police showed up.

United Airlines Flight 23 was bound for the West Coast and full of fuel.

"We are looking at the possibility there may have been more than four planes targeted for hijacking," U.S. Attorney-General John Ashcroft said at the time. However, U.S. officials have not issued more information about the incident, suggesting investigators had put it to rest.

In the weeks after Sept. 11, several other flights were investigated as possible targets for terrorism, but despite the largest criminal investigation in U.S. history, no one has ever been charged in connection with another potential suicide highjacking.

"We don't know; it's not confirmed; there are just possible suspicions," Gen. Pennie said in French. "We think that we had at least another plane that was involved, trying to do the same thing. I don't know the target or other details but we were lucky."

The operations officer at the time that control of North America's airspace was transferred to NORAD happened to be a Canadian naval captain, Gen. Pennie said.

Asked whether the Canadian government, including the Prime Minister and the defence minister, were consulted before NORAD went into active operations on Sept. 11, the general said that communications between NORAD and Ottawa were more laborious than with Washington on Sept. 11.

Gen. Pennie said NORAD has a secure hot-line connection to both Ottawa and Washington but "we had some challenges here. . . . Our connectivity with Ottawa is not as robust as with Washington."

NORAD has been responsible since 1958 for Canada-U.S. air defence co-operation. Its role is now under scrutiny amid potential closer defence relationships between Canada and the United States.

In the largest overhaul of its defence structure since the end of the Second World War, the United States has created a new integrated military zone whose sphere of responsibility spans from the Arctic to Mexico.

It remains unclear whether Canada will join the new command, as it did with NORAD.

The new Northern Command is to become effective in October but little will change at first, Gen. Pennie said, because a lot remains to be planned and negotiated.

He added that much of Northcom's eventual makeup depends on who is chosen to lead it.

U.S. President George W. Bush named U.S. Air Force General Ralph Eberhart, the current NORAD commander, as Northcom's first commander but his nomination still has to be ratified by Congress.