A leaked United Nations report detailing human-rights violations by a Saudi Arabia-led bombing campaign in Yemen has spurred calls in Britain to suspend arms sales to Riyadh and is increasing pressure on the Canadian government to do the same.

The Trudeau government opened the door last week to halting a $15-billion arms sale to Saudi Arabia when it issued a statement saying it reserves the right to do so if events warrant – a shift in message after weeks of framing the Canadian sale of combat vehicles as a done deal.

The UN report is raising fresh hopes among critics of Canada's unprecedented arms deal with Saudi Arabia that Ottawa might finally be persuaded to suspend the sale of weaponized armoured vehicles to a country that already has an abysmal record on human rights. The office of Foreign Affairs Minister Stéphane Dion did not immediately respond Wednesday to requests for comment.

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(The Saudi arms deal: A primer on what we've learned so far)

In a new report obtained by The Guardian, a UN panel investigating the bombing campaign in Yemen has found "widespread and systematic" attacks on civilian targets in violation of international humanitarian law – revelations that are prompting the Official Opposition in Westminster to urge an immediate inquiry and suspension of British arms sales to Saudi Arabia. The Saudis and Arab allies launched a military intervention in Yemen last year in support of President Abd-Rabbu Mansour Hadi who was under threat from Houthi forces aligned with Iran.

Cesar Jaramillo, executive director of Waterloo, Ont.-based Project Ploughshares, an anti-war group that tracks arms sales, said he believes the UN panel's findings should galvanize Canada to act on the Saudi deal.

He noted the report documented "systematic targeting" of civilians in Yemen, rather than simply indiscriminate bombing.

"This report is further evidence of the Saudi regime's utter disregard for human rights," Mr. Jaramillo said.

"Is this not exactly the type of report that Mr. Dion's office said it would consider to determine whether export permits should be suspended or cancelled?"

Last week, Mr. Dion's office announced that while the Liberals had no intention of cancelling the deal, they would not ignore developments in Saudi Arabia and would "factor this information into consideration of future permits." Permits for exports are time-limited and would need to be renewed over the life of Canada's 14-year arms deal with Riyadh.

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According to The Guardian, the new UN report attributes 60 per cent, or 2,682, of civilian deaths and injuries in Yemen to air-launched explosive weapons dropped by the Saudi-led coalition. "The coalition's targeting of civilians through air strikes, either by bombing residential neighbourhoods or by treating the entire cities of Sa'dah and Maran as military targets, is a grave violation of the principles of distinction, proportionality and precaution. In certain cases, the panel found such violations to have been conducted in a widespread and systematic manner."

The federal government has faced repeated requests to justify the shipment of weapons to Saudi Arabia, a country notorious for its atrocious treatment of women, dissidents and prisoners. The Liberals promised during the election campaign that they would revise Ottawa's approach to international relations to improve this country's reputation on the global stage, and marketed this change as "Canada's back."

Opposition parties on Wednesday intensified their demands for the Trudeau government to make public any study or report showing how the Saudi arms deal passes muster under Canada's weapons export regime.

Conservative foreign affairs critic Tony Clement, whose government signed the Saudi arms deal, called on the Liberals to release those deliberations and said it's up to the Liberals to determine if the justification for selling the armoured vehicles is still solid. "Clearly if circumstances have changed, the Government of Canada … should come clean to the Canadian people and we can have a discussion."

NDP foreign affairs critic Hélène Laverdière urged likewise, saying the Liberals themselves were urging the release of this information when they were still in opposition.

The Saudi deal – the largest advanced manufacturing contract in Canadian history – is no ordinary transaction between a Canadian company and a foreign government.

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In this deal, the Canadian government is the prime contractor, responsible for delivery of what are believed to be hundreds if not thousands of combat vehicles to the Saudi Arabian national guard. As The Globe and Mail first reported, LAVs sold to the Saudis will be equipped with anti-tank missile cannons and medium-calibre machine guns.

The former Harper government used its diplomatic resources to lobby the Saudis hard for this contract, and Ottawa is fronting the deal on behalf of General Dynamics Land Systems Canada, a Canadian subsidiary of a major U.S. defence contractor.

The deal will support 3,000 Canadian jobs over 14 years, both in London, Ont., where the vehicles are assembled, as well as across the country.

The contract is currently in the material-procurement stage.

Before an export permit is issued, federal arms-control rules require Ottawa to ensure there is no risk that arms shipped to a country with a poor human-rights record could be used against civilians.

The Liberal government still refuses to release Ottawa's deliberations on the matter, citing commercial confidentiality.