Conservative Leader Stephen Harper slammed Paul Martin over a Liberal attack ad suggesting the Tories would station armed soldiers on the streets of Canadian cities, saying it is an insult to the army and raises question's about the party's credibility.

"A prime minister of Canada should never run an ad that directly or indirectly badly reflects on the military of this country. Our opponent has. I will never do that," Harper told supporters Wednesday.

Many soldiers and retired officers said they were insulted and outraged by the ad that warned Harper would put "soldiers with guns" in Canadian cities. The Liberals say that ad, which appeared on the party website, was pulled before it was ever broadcast.

The ad stems from the Conservative platform which calls for 100 regular troops and 400 reservists to be based in major Canadian cities. But their purpose would be for humanitarian means or disaster relief efforts.

"I guess what it tries to suggest is we would impose martial law or some such thing," he said. "It has not only angered our soldiers and our veterans but raises serious credibility questions. Who believes this," Harper said.

He said the Liberals should be careful because it was their party that invoked the War Measures Act in 1970 during the October Crisis in Quebec.

The ad, he says, raises questions about the Liberals' credibility.

"Voters should be aware, when they see that ad, when they see all these other ads, to have a great deal of skepticism about where this so-called information is coming from, what the context of it is, what the truth is."

Many of the Liberal attack ads quote old speeches Harper made years ago. He admitted his views on specific issues have evolved over time.

"We always, as political leaders, have to respect the fact that circumstances change and you have to deal with the real concerns of people and the real situations that are before us."

Harper also dismissed Martin's speech Wednesday accusing the Tories of having a secret agenda to trample minority rights including a right to an abortion.

"I thought we'd hear today positive ideas from Mr. Martin," Harper said during a campaign stop in Fredericton.

"Instead, we got yet another negative attack speech. And I think that's one of the difficulties with his campaign."

Harper also insisted that he would not reopen the abortion debate.

"A Conservative government will not be bringing forward, will not be supporting, and will not be debating the abortion laws in this country. I've been clear on that and, frankly, I think that's put the matter to rest."