The military has started testing Canadian soldiers for illegal drugs before deploying them to Afghanistan, CTV News has confirmed. But one source said hundreds of troops have apparently failed the test.

"We're told that 1,000 of them have had the test so far, and one source told us that about 300 of them have failed," CTV's Rosemary Thompson reported on Mike Duffy Live Wednesday.

The government has refused to release the test results. But Defence Minister Gordon O'Connor said soldiers who tested positive for illegal drugs -- like marijuana, cocaine and heroin -- will be tested again.

"If troops fail twice, they'll be sent to a drug education program," O'Connor told reporters.

The drug testing policy was proposed last year by Gen. Rick Hillier, chief of Canada's defence staff. The problem of sending potential drug addicts to Afghanistan is compounded by the fact the war-torn country produces mass amounts of opium.

Coincidentally, on Wednesday, Afghan police and NATO troops found more than nine tons of marijuana in a truck in southern Afghanistan.

"We're sending our soldiers to a country where there's a big drug problem with opium and marijuana, so testing makes sense to me," Warrant Officer Mike Aube told CTV News.

Potentially barring hundreds of soldiers from going to Afghanistan comes at a time when military officials are concerned about a shortage of combat-ready troops.

Scott Taylor, editor of Esprit de Corps military magazine, said failing both tests likely will not prevent soldiers from deploying to Afghanistan.

"They are saying they get a second chance, and if there's a significant number (of failures), they are probably still going to have to send them over because operational requirement seems to trump the zero tolerance drug policy," said Taylor.

Hillier still open to 're-rolling'

There are 2,300 Canadian army personnel currently serving in Afghanistan, who rotate through on six-month stints. The Canadian Forces mission is scheduled to remain until at least February 2009, meaning some troops may have to repeat their tours.

Another option is deploying troops serving outside existing combat units, who would then serve alongside infantry -- although they likely wouldn't engage in actual combat.

"Not only are they going to try to make it work with the drug testing, but the chief of defence did assent today to the whole idea of 're-rolling,' or taking people from the air force or navy," said Thompson.

Hillier said Wednesday that sailors and aircrew may be used "to run our convoys," as one potential way to prevent front-line soldiers from serving more than one rotation.

"We're not planning to take sailors and make them infantry," said O'Connor.

He added that troops in support roles, such as mechanics, have about the same qualifications in each branch of the military, meaning a member of the navy could be used by the army.

With a report by CTV's Rosemary Thompson and files from The Canadian Press