OTTAWA -- Canadian and global foreign policy towards Saudi Arabia can't be driven by revulsion over the treatment of individual human rights cases, Canada's most recent ambassador to the country says.

Dennis Horak, who was expelled from Saudi Arabia in August after its rulers were incensed by a tweet from Foreign Affairs Minister Chrystia Freeland, essentially branded the desert kingdom too big to fail.

"Whether we like it or not, the world needs Saudi Arabia … if Saudi Arabia were to descend into the kind of chaos that's potentially there, it would make Syria look like a picnic," Horak told a Tuesday night meeting of the Canadian International Council in Ottawa.

"We need a stable Saudi Arabia, as imperfect as it might be."

Horak, who is no fan of Twitter diplomacy, said Freeland's tweet was "ill-advised" but the Saudi reaction was "way over the top."

Saudi Arabia abruptly severed relations with Canada and demanded an apology after Freeland called for the immediate release of detained activists, including Samar Badawi, a champion of women's rights and the sister of detained blogger Raif Badawi.

On Tuesday, Freeland joined G7 foreign ministers in affirming freedom of the press and calling on Saudi Arabia to conduct a thorough and transparent investigation into the disappearance of journalist Jamal Khashoggi.

But Horak, a veteran diplomat, said Canadian foreign policy can't be dictated by cases like Badawi's -- whose wife lives in Quebec -- or Khashoggi's, whose disappearance has sparked global outrage.

"Those who know me, know I'm not this cold-hearted," said Horak.

"But you can't let your foreign policy be dictated by an individual or an individual case. There are broader interests that need to be there. It doesn't mean you ignore them. It doesn't mean you forget about them."

Khashoggi, a Saudi citizen and a U.S. resident, has written critically of the Saudi regime. He hasn't been seen since entering that country's consulate in Istanbul two weeks ago, and multiple leaks to U.S. media, based on Turkish intelligence, say he was killed by a Saudi hit squad and likely dismembered with a bone saw.

Freeland said Tuesday that Canada is very worried about Khashoggi's disappearance, and she made no apologies for pushing a human rights agenda with Saudi Arabia.

"Canada has raised the issue directly with Saudi Arabia and we are talking about the issue with our allies," Freeland said Tuesday during a question and answer session at the Fortune Global Forum in Toronto.

Freeland said she's been in contact with her G7 and NATO counterparts, including U.S. Secretary of State Mike Pompeo, as well as the German, British and Turkish foreign ministers.

"We think that it is very important that there be a clear, transparent investigation. We need to know what has happened, and those responsible need to be held to account," Freeland said.

Her comments were echoed in a brief statement issued Tuesday by the foreign ministers of G7 countries.

"We remain very troubled by the disappearance of prominent Saudi journalist Jamal Khashoggi," it said.

"We encourage Turkish-Saudi collaboration and look forward to the Kingdom of Saudi Arabia conducting a thorough, credible, transparent, and prompt investigation, as announced."

The allegations that Khashoggi was killed inside the consulate have been strongly denied by Saudi Crown Prince Mohammed bin Salman and King Salman in conversations with U.S. President Donald Trump.

Trump offered his most robust defence of the Saudi regime during a Tuesday interview with The Associated Press, in which he linked the allegations of the Khashoggi case with the recent Brett Kavanaugh affair.

In the interview, Trump compared the case of Khashoggi to the allegations of sexual assault levelled against Kavanaugh during his Supreme Court confirmation hearing.

"Here we go again with, you know, you're guilty until proven innocent. I don't like that. We just went through that with Justice Kavanaugh and he was innocent all the way as far as I'm concerned," Trump told AP.

Freeland also dropped a strong hint that she has no regrets about the tweet that raised the ire of Saudi rulers.

"It's important to have private conversations. But I do think it's a mistake -- and it can be frankly a self-serving mistake -- to think that a private conversation is always an equally effective substitute to taking a public stand," Freeland said.

"And sometimes it's important to take a public stand."

Saudi Arabia also responded by recalling its ambassador in Ottawa, freezing trade, cancelling flights to and from Toronto and recalling its students from Canadian medical schools.

Freeland said she's been in regular contact with her Saudi counterpart, but she had nothing new to report on Tuesday.