Prime Minister Stephen Harper suggests his party's recent ad campaign that included controversial attacks against Liberal leader Michael Ignatieff may have done Canadians a favour.

In an interview with CTV News in Halifax, the prime minister told CTV Atlantic's Steve Murphy that the ads help convince the Liberals not to trigger a summer election, and allowed his Conservative minority government a few months of breathing space.

"To the extent that I think that the ads made the Liberal Party think twice about having an election, I think that's been a good result," Harper said.

"Because I don't think Canadians want an election, I think it would have been another round of political instability. And so to the extent I think it's put that party a little bit back on its heels. It may be thinking a little bit more about how to co-operate in actually dealing with the economy -- I think it's been helpful."

The ads criticize Ignatieff's time outside the country, alleging the Liberal leader returned to Canada solely to seek the prime minister's job.

Harper refused to say whether he personally agreed with the ad's sentiments that Igatieff is "just visiting." He said he would leave it to voters to decide whether Ignatieff's 34 years outside Canada disqualified him to be prime minister.

"Those ads are built around his [Ignatieff's] own record, his own words, on his own motives and his own statements on the country. Those are questions he will have to answer... As I say, the ads allow Mr. Ignatieff to speak for himself," Harper said during the 10-minute interview.

Harper said the ads ran at a time when the Liberals were not co-operating in the operation of Parliament.

"My preference would be for the opposition to work with the government. The Opposition has not chosen that path until very recently," Harper explained.

"I do think the people want to see the parties work together. But, certainly if the parties aren't going to work together, the Conservative Party won't unilaterally disarm."

One week ago, Ignatieff and Harper reached a deal that prevented a summer election. Thursday's comments come as Parliament begins its summer break. It's expected all parties will use the time to test the waters for a fall election campaign.

The opposition will have an opportunity to put forward a non-confidence motion during an opposition day early in the fall session.