Prime Minister Stephen Harper says he will attend a major meeting on climate change in Copenhagen next month after all, although he has downplayed the possibility of a global deal on climate change.

A spokesperson for the Prime Minister's Office made the announcement on Thursday, a day after U.S. President Barack Obama said he would attend the climate change meeting.

Harper spokesperson Dimitri Soudas said the prime minister would attend the conference because a "critical mass" of leaders would now be attending.

Originally Harper had designated Environment Minister Jim Prentice to head the Canadian delegation. And as recently as Wednesday, the prime minister said he would not be travelling to the Danish capital.

But CTV's Roger Smith, who is traveling with Harper to a conference of Commonwealth states in Trinidad and Tobago, said the growing number of national leaders who plan to attend the Copenhagen meeting had made it politically unfeasible for the prime minister to stay away.

"I think the calculation here is that if 65 other leaders including the American president are going to Copenhagen, it wouldn't be wise for the prime minister to stay home," Smith told CTV News Channel Smith by phone from Harper's plane.

"Even if there's no deal he can at least say he went and took part in the negotiations," he said.

Liberal Leader Michael Ignatieff mocked Harper's about face.

"What a coincidence," Ignatieff said in Quebec City. "He's been dragged there by the decision of the president to go there."

Obama will attend the third day of the Dec. 7-18 conference. It is not clear when Harper will attend.

Harper has "been very clear that he will go to Copenhagen, that he will participate in Copenhagen. The exact time at which he will be participating hasn't yet been determined," Prentice said.

Politicians from around the world are scheduled to meet in the Danish capital from Dec. 6 to 18 to try to piece together a new climate-change agreement. The Kyoto Protocol is due to expire in 2012. It's not clear what portion of the two-week gathering Harper will attend.

Canada has become the target of international criticism for going back on its Kyoto commitments, and for refusing to sign a new agreement unless it includes commitments for developing nations to reduce their greenhouse gas emissions.

That position has dimmed hopes that developed and developing countries will be able to achieve consensus on climate-change in Copenhagen.

The timing of Harper's announcement may help temper criticism Canada may face at the Commonwealth meeting Harper is traveling to, Smith said. Many Caribbean countries fear being swamped by rising sea levels that global warming is expected to cause.

With files from The Canadian Press