The Canadian Forces have announced they will deploy more armoured patrols in place of light Iltis jeeps in high-risk areas in Afghanistan.

"We'll offer more protection to patrol members,'' Para Company Sgt.-Maj. Wayne Bartlett said. "We're going to use vehicles differently where we think there is a potential threat."

The decision came after preliminary investigations showed the explosion that killed two Canadian soldiers and injured three others on the outskirts of Kabul last week was likely a deliberate attack.

"There is a strong possibility it was a deliberate attack," Major Kevin Arata, a spokesman for the NATO-led International Security Assistance Force (ISAF), told Reuters.

Last Thursday, Sgt. Robert Short and Cpl. Robbie Beerenfenger were killed when the vehicle they were travelling in was hit by an explosive device.

Until now, military officials were unsure exactly what caused the blast. A preliminary report given to Maj.-Gen. Andrew Leslie, commander of Canadian Forces in Afghanistan, on Tuesday said the explosion was most likely caused by at least one Soviet-made TM-57 anti-tank mine "designed to kill or immobilize a main battle tank."

"The inference is that the mine was planted in the ground," said Leslie. "How many mines? We know that there were three explosive devices."

Earlier Tuesday, Canadian, British and German forces assisting Kabul police took into custody Abu Bakr, a local man they said was a terrorist leader who may be responsible for the explosion.

Abu Bakr is the most senior commander in Afghanistan's third-largest terrorist organization -- Herb-e-Islami Gulbuddin or HIG. He has been linked to the suicide bombing of a German bus last spring in which four German soldiers were killed and 29 others wounded, as well as attacks on other foreign troops in Afghanistan.

"We have indications he is under orders to orchestrate attacks on ISAF personnel using rockets and mines," said Maj.-Gen. Andrew Leslie, the commander of Canadian Forces in Afghanistan.

"Should this turn out to be conclusively an attack, we may well have apprehended the man who ordered" the suspected attack on Canadian troops, he said.

Another ISAF source said there is no current indication Bakr had been involved in the incident, according to Reuters.

The blast left the vehicle broken in half and barely recognizable. The back rear-quarter was completely missing and pieces of the Iltis were found up to 150 metres from the blast site. The crater itself had about three blast marks inside. It was about the size of a hot tub.

The soldiers were travelling on a route they had been cleared of mines just 24 hours earlier, leaving some to suspect that someone had replaced the mines in a targeted attack against members of the ISAF, of which Canada is the largest contributor.

CTV's Matt McClure, reporting from Kabul, said videotape and pictures of the bombing shows that the crater left by the mine is directly in the tracks of where Canadian military vehicle had passed just three hours earlier.

"They also say that there is no indication that the Canadian vehicles that were involved in this incident, those Iltis jeeps, deviated from those tracks."

That suggests the mine, or mines, was freshly laid in a deliberate attack and not just an old weapon left over from Afghanistan's long civil war.

A washingtonpost.com reporter who took video of the Canadian victims just two days before their death said the arrest seems consistent with his story.

"The arrests that happened today, it seems to fit the story appropriately," Travis Fox told CTV's Canada AM. "This route that they were travelling, they had travelled it before. The area was known to be safe.

"So it seems like a good explanation that this was planted after the fact. Planted recently."

Close to 2,000 Canadian troops are posted in Kabul as part of the NATO-led ISAF. Its mandate is to secure the capital and provide protection for the interim government of President Hamid Karzai.

With a report from The Canadian Press