Prime Minister Stephen Harper waded into the incendiary debate over Liberal leadership front-runner Michael Ignatieff's charge that Israel has committed a "war crime" in Lebanon, blasting the entire Grit hopeful lineup for what he called their "anti-Israeli position."

When asked about the term "war crime" to describe Israel's action against Hezbollah in Lebanon, Harper told reporters at a press conference on Thursday that he found the usage inappropriate, saying "I don't support that view."

But the prime minister went one step further, taking a jab not only at Ignatieff, but the entire lineup of Liberal leadership hopefuls.

"This is consistent with the anti-Israeli position that has been taken with virtually all of the candidates of the Liberal leadership, and I don't think it's helpful or useful."

Ignatieff's Liberal leadership rivals begged to differ.

Bob Rae told CTV's Mike Duffy Live that he expects an apology from the prime minister.

"I just think it's absolutely appalling to lie and smear in this way," Rae said.

Earlier, Rae noted to reporters that his wife and family are Jewish and said that Harper should be embarrassed to make such a "disgraceful" and "divisive" comment.

"The prime minister knows it isn't true -- I don't know why he would say such a thing except he's trying to get a kind of a reaction," he said.

Fellow leadership hopeful Stephane Dion said Harper's accusation was "disgraceful" and not very "prime ministerial," but urged Ignatieff to justify his statement that Israel had committed a war crime.

Ignatieff issued a statement Thursday that accused Harper of "playing crass politics with the issue of the Middle East. It's beneath him and his office to do so."

The Liberal Party has always been a friend of Israel, Ignatieff's statement said, and will stand "shoulder to shoulder with Israel and the Canadian Jewish community to defend Israel's right to respond when attacked by terrorists or when its neighbors wrongfully deny its right to exist."

Gerard Kennedy, another Liberal gunning for the party's top job, said Harper's comment was "really beneath the office of the prime minister" and accused him of "looking after his political well-being" ahead of Canada's.

"He could be called upon tonight to say something serious about the Middle East," said Kennedy, "and he is losing the capacity to do that because he's playing this partisan advantage."

Asked about Ignatieff's war-crime remarks, Kennedy said that he found it confusing and puzzling, and he's "having a hard time reconciling them with the available information." Kennedy said he hopes "there's a better explanation for this than has been in the news so far."

Liberal leadership contender Joe Volpe characterized Ignatieff's comments as "a rookie error."

Ignatieff's missteps

In an ironic twist, Ignatieff was attempting to explain a previous gaffe on the same subject when he dug himself into a deeper hole.

In an interview broadcast Sunday on Quebec talk show "Tout le monde en parle," Ignatieff apologized for telling the Toronto Star in August that he was "not losing sleep" over an Israeli air strike that killed dozens of Lebanese civilians in the village of Qana on July 30.

"I showed a lack of compassion. It was a mistake and when you make a mistake like that, you have to admit it," he said in French.

"I was a professor of human rights, and I am also a professor of the laws of war, and what happened in Qana was a war crime, and I should have said that."

Earlier in August, Ignatieff admitted that he made a "mistake" in his comments to the Star; and since then transcripts of his interview shows that he prefaced those comments by calling the Qana bombing a "tragedy" for the Lebanese people.

But the interview in Quebec on Sunday marks the first time he has characterized Israel's actions as a war crime. His comments highlighted divisions not only within his inner circle but within the Liberal party itself.

The co-chair of Ignatieff's Toronto campaign, Thornhill MP Susan Kadis, announced Wednesday that she was quitting over his remarks.

Kadis said she found his comments "troubling," given that Israel was defending itself in its conflict with Hezbollah.

Jewish leaders also reacted angrily to Ignatieff's latest choice of words and demanded a retraction.

Ignatieff so far has the support of nearly 30 per cent of delegates in the battle for the Liberal leadership, with the less than two months to go before the Nov. 28-Dec. 3 Liberal convention in Montreal.

Harper taking heat

Harper, who has been perceived as pro-Israeli, has come under fire himself for taking sides in the Mideast conflict.

He made waves in international waters in September, when members of the Francophonie summit agreed to a compromise on a contentious resolution after Harper blocked the original proposal.

The original wording of the resolution recognized Lebanon's suffering in this summer's 34-day conflict, but not Israel's.

Harper took a strong stance against the Egyptian-proposed resolution, which most of the 72 members supported. He urged the organization to recognize the suffering of both nations.

The French-speaking states eventually agreed unanimously to support a compromise that called for the end of hostilities and a return to calm.