The U.S. military's investigation into last week's bombing incident in Afghanistan that killed four Canadian soldiers could take up to two months to complete, officials said Monday.

Gen. Tommy Franks, commander of the Afghan war, has ordered the investigation, according to a statement issued Monday by his Central Command headquarters.

Four Canadians were killed and eight injured when an American F-16 pilot on a nighttime air patrol apparently mistook the Canadians for enemy forces. He thought he was acting in self-defense when he dropped a 500-pound bomb on them in the early morning hours of Thursday, U.S. officials said.

The Canadians were conducting a live-fire training exercise near the southern Afghan city of Kandahar.

The investigation "will make an assessment as to any fault or neglect and make recommendations concerning corrective measures and disciplinary actions, as appropriate," the statement said.

The investigation will be concluded in 30 to 60 days, it said.

A Canadian board of inquiry began its own investigation Monday. The five-member board, headed by former defense chief Maurice Baril, a retired general, is scheduled to file an interim report to Defense Minister Art Eggleton within three weeks. The final report is expected within 60 days.

Baril said Friday that he will have access to all the evidence obtained by U.S. investigators. Canada's inquiry board will include Brig. Gen. Marc Dumais, who will also sit on the U.S. panel of investigators.

President Bush, who telephoned Canadian Prime Minister Jean Chretien immediately after the accident, touched a nerve in the Canadian press when he made no public comment about the accident all day Thursday except for a written statement released late in the afternoon.

Friday morning editions of the Toronto Globe and Mail carried a headline that read, "Deaths don't merit a mention from Bush; U.S. indifference."

On Friday, Bush pledged to reporters: "We'll find out what happened. It was a terrible accident."

The Canadians were from the 3rd Battalion of the Princess Patricia's Canadian Light Infantry, based near Edmonton, Alberta.

The investigators are expected to determine why the pilot apparently did not know the Canadians were there. All allied troops operating in the Kandahar area are supposed to be aware of friendly forces.

A Canadian representative at Franks' headquarters in Tampa, Fla., Capt. Isabelle Compagnon, said last week that the investigation would be a joint U.S.-Canadian effort. It would determine whether the Canadians had followed normal procedures in notifying other coalition forces, including the Americans, of the time and place of their training exercise, she said.