KABUL — One of Canada's spy planes has crashed and has gone missing in Afghanistan, almost two months to the day after another crash that temporarily halted the unmanned surveillance aircraft, or UAV, program.

"We don't know what happened," said Maj. Dyrald Cross. "All we know is that it crashed."

That leaves the Canadian Forces in Kabul with no more planes. They had four of them, but two others were damaged in "hard landings." A plane that crashed on Nov. 21 was the first to be destroyed after its parachute failed to open as the aircraft descended.

"This (latest) one, the causes are undetermined at the moment," said Cross, who is in charge of the UAV program.

When the plane went down unexpectedly Tuesday, controllers were unable to pinpoint the crash site before dark. A crew of soldiers deployed to search out the aircraft were also unsuccessful in locating it.

"We haven't found it yet," said Cross.

"We know roughly where it is, but it was too dark so we're waiting until (Wednesday) morning to make sure the area is safe and have a better opportunity to find it in the daylight."

Unlike commercial or manned aircraft, the UAV contains no beacons to direct searchers to its location. However, the software included in the machine can be tracked through a satellite-based Global Positioning System.

"We have its last GPS reading," added Cross.

An investigation will be launched to determine why the plane's 65-horsepower Bombardier snowmobile engine shut down unexpectedly, causing the 3½-metre-long plane to fall to the ground.

The spy planes had been used by the NATO-led International Security Assistance Force since mid-December, when testing of the $33-million, high-reconnaissance system was completed.

The UAVs are launched by catapult from the back of a truck, and travel at 40 metres per second, capturing video through cameras mounted in a ball on the underside of the aircraft.

There is also a forward-looking, wide-angle camera mounted in the UAV's nose from which ground "pilots" can fly the aircraft by sight.

Built by Sagem of France, a subsidiary of Orlicon Canada, the planes were able to peer down on Kabul and the city's surrounding mountains to provide surveillance information to soldiers on the ground.

In fact, it was used to aid Canadian soldiers as they raided a compound in the Afghan capital Sunday in search of drug smugglers with possible connections to a terrorist organization.

On Tuesday, Lt.-Col. Don Denne confirmed that evidence was found "linking the compound and those therein to both drug trafficking and terrorist groups."

However, when pressed, Denne said he couldn't provide further details, citing security concerns.

"We've got certain items of interest including weapons, small amounts of narcotics and cash," he added without getting specific.

"We don't want anybody out there, and especially a terrorist group, to know what we are interested in, what we have found."

Sixteen men were detained during the raid. Five of them were brought to Camp Julien where they were questioned by the Canadian military, while the rest were turned over to Kabul police. The five detained at the Canadian base were subsequently also handed over to police, although it's unclear whether any charges have been laid or whether any of the 16 remain in custody.

Canadian military officials had earlier cited intelligence sources who linked at least some of the men to Gulbuddin Hikmatyar, founder of the radical Muslim terrorist group Hizb-I Islami Gulbuddin (HIG), an organization with long-established ties to Osama Bin Ladin.

Denne is commanding officer of Camp Julien near Kabul, home to most of the nearly 2,000 Canadian soldiers working in Afghanistan under the ISAF umbrella.