A Canadian citizen has been detained by Afghan police on suspicion of attending a militant training camp in southern Afghanistan.
MacKay said Canadian officials have visited the man, who is being held for investigation in Kabul.
"He's being given consular services from our embassy there," MacKay said.
Authorities did not say when or where in Afghanistan the man was detained and offered no other details.
But the Globe and Mail newspaper reported Friday he is a 24-year-old of Pakistani origin who had previously lived in Calgary. The newspaper said he was taken into custody at a Kabul bus station within the past few days.
"At this point in time, for privacy reasons, we're not at liberty to say a lot about this case, but it is somewhat unusual," MacKay said.
Foreign Affairs officials would not release the man's name, citing the Privacy Act.
The man was carrying a Canadian passport at the time of his arrest, officials said.
Canadian officials say they expect to have access to the man as long as he remains in custody.