Canadian Prime Minister Stephen Harper pauses during the news conference at the end of the G8 summit. (Chris Wattie/Reuters)

Prime Minister Stephen Harper apologized Friday after he publicly attacked his rival Michael Ignatieff for a comment the Liberal leader never made.

"I learned shortly after the press conference this was not a quotation of Mr. Ignatieff," Harper said after the Group of Eight summit in Italy. "I regret the error and I apologize to Mr. Ignatieff for this error."

Harper, during a closing news conference at the summit in L'Aquila, wrongly criticized Ignatieff for saying Canada could become irrelevant at major international summits.

"Mr. Ignatieff is supposed to be a Canadian," Harper said. "I don't think you go out and throw out ideas like this that are so obviously contrary to a country's interest and nobody else is advocating them."

But Ignatieff never made the comments, former Canadian diplomat Gordon Smith did. Smith, director of the Centre for Global Studies at the University of Victoria, has said Canada needs to take a leadership role or risk losing importance.

One of Harper's senior assistants, Dimitri Soudas, has stepped forward to take the blame for the misattribution and for misinforming his boss.

Ignatieff, in a written statement, said he accepts the prime minister's apology.

"It's unfortunate that these remarks have come at the end of the G8 meeting when Canada's efforts would have been better spent engaging with global leaders on shared issues," the statement said.