Canada's contribution of one C-17 military transport plane to help support the French mission in Mali was due to end on Friday.
"I can confirm that we will be extending our support for the Mali mission for an additional 30 days," Mackay told reporters in Ottawa after question period.
"The C-17 aircraft will be made available to the French for that specific use, on an as-needed basis, for an additional 30 days. So that will take us out to March 15," Mackay said.
NDP foreign affairs critic Paul Dewar said the 30-day extension was a surprise.
Dewar said the foreign affairs and international committee held another briefing on the situation in Mali earlier today but that Conservative MPs did not mention the extension.
MacKay told reporters the federal government received the request "a few days ago."
"It was a request that came to us through military channels and so we wanted to examine the specifics of what that would entail and how it would fit with ongoing operational requirements of the Canadian Forces," he said.
Canada contributing humanitarian aid
Last Thursday, during another meeting of the foreign affairs and international committee, the French and Malian ambassadors to Canada briefed members of Parliament on the conflict in Mali but neither envoy made any additional request for further contributions from Canada.
On Tuesday, MPs took part in a four-hour 'take-note' debate on the conflict in Mali and Canada's contribution to the mission.
Bob Dechert, the parliamentary secretary to the foreign affairs minister, said the 'take-note' debate was "only one part" of the federal government's commitment to engage MPs on Canada's reaction to the conflict in Mali.
But Dewar said the Opposition New Democrats were not consulted on the second extension.
The Conservatives had said that "they were going to consult, they said they would be open. Instead, what we have seen is that they have kept it from us and announced it just before the commitment was up," Dewar said.
Canada pledged $13 million, last month, in new money to support humanitarian relief in Mali.
Special forces are also on the ground protecting Canadian assets such as the Canadian Embassy in the capital Bamako.
The special forces are not related to the 40 Canadian troops who have been piloting and supporting the C-17 transport plane.
This is the second extension in support of the French military mission in Mali.
The federal government originally made the C-17 available to France for one week, but then extended its commitment by another three weeks, to Feb. 15.