Foreign Affairs Minister Stéphane Dion is defending a controversial $15-billion arms deal with Saudi Arabia by saying cancelling it would be a futile gesture because another country would simply supply the combat vehicles to Riyadh instead.

"It would not have an effect on human rights in Saudi Arabia," Mr. Dion predicted, if the Liberals were to scrap a 14-year lucrative contract to build fighting machines that will be equipped with machine guns or anti-tank weapons.

International censure of Saudi Arabia is on the increase as rights groups decry an erosion of human rights under the current leadership there. Only two weeks ago, the Dutch parliament voted to stop arms shipments to Saudi Arabia, and in February, the European Parliament passed a motion calling for the suspension of weapons sales to Riyadh.

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Mr. Dion used a Monday speech on the Liberals' foreign policy to mount a hard-nosed defence of what is Canada's largest-ever manufacturing contract – a transaction that was brokered by Ottawa under the former Conservative government and will benefit defence contractor General Dynamics' London, Ont., plant until 2028.

"Riyadh does not care if the equipment comes from a factory in Lima, Ohio or Sterling Heights, Mich., rather than one in London, Ont.," Mr. Dion said, naming American cities where military suppliers such as General Dynamics have a presence.

More than 2,000 workers in Canada would lose their jobs if the government cancelled the deal, the minister predicted.

Louise Arbour, a former United Nations High Commissioner for Human Rights who once sat on the Supreme Court of Canada, was in the audience for Mr. Dion's speech, and she said the contention that some other country would just take over the contract is "the weakest argument" that could be made.

"This argument that if we don't do it somebody else will do it I find, frankly, the least convincing," she said. "It is not infused with moral, ethical values."

She said there are better reasons to justify sticking with the Saudi deal and would like to see Mr. Dion "do a balancing of consequences," such as reputational, financial, jobs and the impact of doing nothing at all, including "Canada being seen as validating a regime that is at odds with a lot of Canadian values."

Ms. Arbour said she hopes the federal government applies more rigour to examining weapons export permits, as it has repeatedly promised.

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Mr. Dion signalled impatience and irritation at ongoing media coverage of the arms agreement as the Liberals grapple to deal with ongoing questions about a massive contract with a country that is regularly ranked among "the worst of the worst" on human rights by Freedom House. He was asked by a broadcast journalist how he could defend doing business with Saudi Arabia given its reputation for human rights.

"I did in the speech. Read the speech. I am repeating the same things month after month after month," Mr. Dion said, sounding exasperated.

The Foreign Affairs Minister distanced himself Monday from comments made in January by Jocelyn Coulon, an academic and former journalist who joined Mr. Dion's office in February.

Saudi Arabia has "bought the silence" of Western countries by awarding them lucrative contracts to supply it with military and civilian goods, Mr. Coulon wrote in La Presse just six weeks before he began work for Mr. Dion. This statement is at odds with the Trudeau government's repeated insistence that it can effectively stand up to Saudi Arabia on human rights while overseeing this unprecedented arms deal with Riyadh.

Mr. Dion declined to comment on Mr. Coulon, but when pressed, he said the Liberals are incorruptible. "It's impossible to [buy] off this government," he said.

Cesar Jaramillo, executive director of the anti-war group Project Ploughshares, which monitors weapons exports, said Mr. Dion is wrong to say it makes no difference whether Canada supplies the arms or not.

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"In one scenario, Canada could be indirectly complicit in human-rights violations; in the other, it would uphold the core values of the vast majority of Canadians and enhance its international credibility as a champion of human rights," Mr. Jaramillo said. "Take your pick."

Mr. Dion's argument that cancelling the deal would be futile because another country would step up to supply the armoured vehicles drew mocking criticism on Twitter on Monday. "I'm thinking of making extra cash as a hired hit man. I mean, if I don't do it someone else will right?" Canadian comedian Scott Vrooman tweeted.

Saudi Arabia's conduct in the war in Yemen against Houthi rebels aligned with Iran has drawn unanimous condemnation from rights activists. Both Amnesty International and Human Rights Watch have called for arms embargoes against Riyadh over what a UN report has called indiscriminate bombing of civilians.