An urgent review has been ordered into Canada's airport security after a video posted on YouTube showed two fully veiled women boarding a plane to London without showing their faces.
The video shows a group of passengers boarding an Air Canada flight from Montreal's Pierre-Elliott Trudeau airport to London's Heathrow airport on July 11.
The handheld video, shot by a British traveller, shows a man boarding a flight with four women, two with face veils, two without.
The man hands their passports, and the veiled women are allowed to board, without showing their faces to confirm their faces match those on their passports.
The footage is shot at a distance and it is impossible to see what happens next.
A British lorry driver identified as Mick, who took the video, wrote on his YouTube site: 'I complained, both at the check-in desk and also when I was boarding the plane'.
An Air Canada spokesman declined to comment on the incident, but said the Canadian Air Transport Security Authority is responsible for security screening, and passengers undergo multiple checks before arriving at the boarding gate.
Canada's Minister of Transportation John Baird ordered the investigation to ensure that airline personnel are checking the identity of all of passengers before they board a flight.
If the reports are true, the situation is deeply disturbing and poses a serious threat to the security of the air travelling public,' Baird said.
'If our current security policies in this area are deemed to be lacking, our government will take the necessary steps to protect the safety and security of the travelling public'.
'I've asked my departmental officials to conduct a full investigation to ensure that we have one law that applies to all,' he said.
Mr Baird added that under Canadian law, airlines must be able to verify the identity of all passengers before they board a flight and have procedures in place to check anyone whose face is covered - regardless of a person's religion.
A spokesman for the UK Borders Agency said: 'Women wearing burkas are required to show their faces on arrival in the UK.
'They can request to be seen by a female Border Force Officer who can take them to a private room to remove the burka if required.