Questions are being raised about whether the explosion that killed two Canadian peacekeepers in Afghanistan on Thursday was a landmine accident or a deliberate act of sabotage. Engineers had cleared the road of mines just one day before the incident.

Canadian peacekeeping officials in Afghanistan have identified the two Canadians killed as Sergeant Robert Short and Corporal Robbie Beerenfenger.

Both were serving with the International Security Assistance Force, known as ISAF, a NATO-led mission operating in and around the Afghan capital of Kabul.

The two had been part of a patrol just southwest of the city, traveling a newly opened route to provide security for a nearby ISAF base.

Initial ISAF reports said the two-vehicle patrol struck a landmine, killing the two peacekeepers and injuring three others.

But Lieutenant-Colonel Don Denne, commander of the Canadian unit involved in the incident, says the track the vehicles were on was in a well-visited area and had just been tested for mines by engineers.

Experts are now examining the scene to determine whether the explosion was in fact caused by a landmine, and whether it was recently planted or was simply an old device left over from Afghanistan's two decades of war.

Major John Vass, also a member of the victim's military unit, says the scene of the incident was a grizzly one.

"The site was very disturbing, extremely surreal, and it was unbelievable," he said. "It looked like something we would set up for an exercise, but of course, unfortunately, this was not an exercise."

Major Vass could not specify the exact size of the explosion crater, but described it as "bigger than a soccer ball."

The deaths mark the first ISAF casualties since June, when a group of German peacekeepers were killed while on their way to the Kabul airport for a flight home.

A memorial ceremony is planned for the fallen Canadian soldiers Saturday.