Passengers headed for the United States will still have to remove their shoes at security checks to comply with stricter rules. (Peter Morrison/Associated Press)

Canada's airport security agency in Ottawa has issued a bulletin to front-line officers instructing them they cannot require domestic or international passengers to doff footwear before walking through metal detectors.

The document, issued in April, was obtained by The Canadian Press under the Access to Information Act and released Monday.

"Never suggest, ask or demand that passengers remove footwear prior to entering the WTMD [walk-through metal detector]," says the one-page directive, which went into effect immediately.

The one major exception, however, is officers can still order passengers heading for the United States to remove their shoes, consistent with higher air-security standards set by Washington.

As well, if a hand-held metal detector signals an alarm for shoes after the walk-through, a passenger can be required to remove their footwear for examination.

"If a passenger offers to remove footwear, allow them to do so," adds the directive.

The Canadian Air Transport Security Authority, or CATSA, says the new guideline will be written into the next edition of its operating manual.

Typically, shoes that passengers have been required to remove are sent through hand-baggage X-ray machines for closer inspection.

Footwear came under greater scrutiny by airport security officers around the world after British citizen Richard Reid was arrested in late 2001 for a failed attempt to bomb an American Airlines flight to Miami by igniting explosives hidden in his shoes.

A flight attendant managed to stop Reid as he tried to hold a match to a fuse sticking out of the heel of one shoe.

But the shoe directive for Canadian screeners appears at odds with a "notice to passengers," currently posted on the CATSA website, that says "all passengers boarding any flights may also be requested to remove footwear for additional screening."

A spokesman for the authority said the spring bulletin is nothing new.

"It's a reminder to screening officers about the existing policy," Mathieu Larocque said in an interview. "The purpose of the bulletin was simply to reinforce an existing policy. Nothing has changed.... We're striving for consistency."

The agency does not keep detailed records of complaints to indicate whether shoe removal is an issue for travellers, Larocque said.

Tougher rules for shoe screening that followed the Reid arrest have prompted a raft of passenger complaints around the world. Numerous blogs and travel websites allege that foot diseases are being spread and that security checkpoints are needlessly clogged by people struggling with shoelaces.