OTTAWA -- Just as what it delivers is changing dramatically, Canada Post must make difficult changes to keep pace in the digital world, the head of Crown agency told a Commons committee Wednesday.

In defending the corporation's proposed service cuts and price hikes, Canada Post CEO Deepak Chopra told the Commons transport committee the changes are necessary in order for the carrier to survive.

"If the mail is changing its shape and size, don't we think the mailbox should change its shape and size too?" Chopra asked.

"So what we're trying to do is adapt (to) the changing needs of Canadians."

It was the first time Chopra spoke publicly since the announcement last Wednesday that Canada Post plans to phase out door-to-door mail delivery in urban centres over a five-year period -- something the corporation's union says it will fight to the last breath.

Instead, mail would be delivered to communal neighbourhood "superboxes."

Under the proposal, the cost of stamps who also rise sharply, by more than 50 per cent.

Chopra struck a positive tone during his nearly one-hour appearance at the committee, but said difficult choices had to be made.

"We believe Canada Post will remain a relevant, meaningful participant in the lives of Canadians," he said.

"Over the years the mail has changed in shape and size, and so are we."

That change, said Chopra, means concentrating more on delivering packages and less on putting paper letters in mail slots.

He told the committee that, in 2007, Canada Post profits began to drop off as people and businesses turned to digital communication.

That decline picked up speed in 2010, he said, with the introduction of computer tablets.

Chopra also cited a recent report that warned, without significant changes, Canada Post could be losing $1 billion a year by 2020.

The post office union, however, questioned that assessment, and also asked why Canada Post hasn't tried more aggressively to expand its revenue base.

"We accept the fact that things are changing," said Denis Lemelin, president of the Canadian Union of Postal Workers.

"However, we cannot understand why Canada Post will not follow the example of post offices in the U.K., in France, in Italy, in Switzerland and in many other countries which are currently either beginning a banking service or expanding their existing services."

Lemelin vowed that CUPW would do everything in its power to reverse the proposed service cuts.

NDP committee member Hoang Mai questioned whether the postal service consulted widely enough before coming up with its restructuring plan, saying he's heard from people who are outraged over the proposals.

"When you made the announcement, people really came out," Mai told Chopra.

"People find it terrible."

Liberal MP David McGuinty warned that the elderly and disabled will face difficulties retrieving mail once door-to-door delivery ends.

But Chopra said the agency had consulted with Canadians for months, and has been mindful of seniors' concerns in putting together its reform proposals.