The Official Opposition has launched new salvos against Defence Minister Peter MacKay's credibility over revelations about his controversial 2010 ride on a military helicopter from a central Newfoundland fishing camp.

Postmedia News reported earlier this week it has obtained emails that show government officials did not want MacKay to attend an Ontario news conference that prompted use of a Cormorant helicopter in July 2010.

As well, the emails appear to contradict MacKay's assertions that the chopper ride was arranged at the last minute, and that officials knew 11 days in advance of the event that critics have slammed as a "photo op."

Defence critic Jack Harris hammered MacKay in the House of Commons on Monday.

"We now have learned that — contrary to what the prime minister told Canadians — the minister of national defence used a search and rescue helicopter to go to what was, in fact, an event planned very much in advance," Harris said.

"But the prime minister said the minister was called back from vacation, and an email released to the media called the event 'unexpected.' Why is it that the government has a bottomless supply of denial and coverup for the minister?" Harris asked during question period.

MacKay fired back, and maintained that the explanation he has given since 2011, when the story surfaced, is accurate.

"As I have said in the House many times, I was called back to work early," MacKay said.

"That is exactly what happened. I was called back from personal time early," he said, adding that the Conservatives have dramatically reduced use of government aircraft.

Liberal raises spectre of Labrador tragedy

Liberal critic Judy Foote also raised the issue, and linked it to the first anniversary of the loss of Burton Winters, the Labrador teenager who perished on coastal ice after getting lost. His family and supporters have called for a public inquiry into how the search for him was handled.

"This new revelation comes on the anniversary of the tragic death of Burton Winters on the ice in Labrador," Foote said.

"The young man lost his life after search and rescue assets were held back because they might be needed elsewhere. The question remains, why was the chopper available for the minister but not for an emergency in Makkovik? Where is the public inquiry to ensure this never happens again?" Foote said.

"With respect to young Burton Winters, this was indeed a tragedy. We send our condolences again to his family and those of the community," MacKay told the House.

MacKay said that DND has updated its procedures, and that it is working better with the provinces on coordinating ground searches.

He added that DND has added a Griffin helicopter to its fleet at Happy Valley-Goose Bay.