The issue has come to light because of a report earlier this month by the U.S.-based group Human Rights Watch that said a Saudi-led coalition may have used the banned weapons while bombing Shiite rebels in Yemen.
Canada and Saudi Arabia, along with the United States, are among the half-dozen countries in another coalition that is currently engaged in bombing missions against the Islamic State of Iraq and the Levant in Syria.
Regardless of Canada's activities in Syria, it has an international legal obligation to speak out because it ratified the United Nations treaty to ban cluster bombs, said Steve Goose, the head of the arms division of Human Rights Watch.
"They could have done a demarche or something," said Goose, referring to the use of a standard, behind-the-scenes diplomatic notice. But that would not have been enough, he added.
"Publicly speaking out is the best way to do this because that's how you stigmatize the weapon. That's how you generate outrage against it, and that's the best way to discourage any use."
An emailed statement from the Foreign Affairs department on Monday said Canada would pursue opportunities "to discourage the use of cluster munitions by states not party to the convention."
The statement did not directly answer a question about whether Canada had raised the Human Rights Watch report with Saudi officials.
"We will continue to engage with Saudi Arabia on a range of issues including regional security and human rights," it said.
Goose said other countries have publicly called out the Saudis on the report, including Costa Rica, which holds the rotating chair of the cluster bomb convention, and Norway, which took the lead in creating it.
Paul Hannon, the executive director of Mines Action Canada, said the government has an obligation to tell its coalition partners that it won't use cluster munitions and that they shouldn't either.
"Historically, use of cluster munitions has resulted in at least 94 per cent of the casualties being civilians," said Hannon.
"If we want to create stability in this region, no one should ever use cluster munitions because of the deadly legacy they leave behind."
A single cluster bomb contains hundreds of brightly coloured, baseball-size submunitions that often fail to explode and can sit dormant for decades. They pose an ongoing hazard to civilians, especially children, in dozens of post-war countries.
The Harper government faced widespread international criticism for undermining the cluster bomb treaty, which it took more than six years to ratify.
The government was broadly condemned because the legislation that it used to ratify the treaty contained a loophole that would allow the Canadian Forces to be involved in the use of cluster bombs in joint operations with the United States, which has opted out of the convention.
Its critics included the usually neutral International Committee of the Red Cross.
The government eventually agreed to remove the word "using" from the bill, which prohibits Canadian military personnel from directly using the weapons, but doesn't entirely bar their indirect involvement in combined operations.
Goose said anti-cluster bomb advocates are happy Canada finally ratified the convention, and there is hope it will be a good partner in preventing the weapons from being used.
But he added one caveat.
"We will closely monitor Canada's implementation because of the extreme weakness of its legislation implementing the convention," said Goose.
"We don't think Canada will ever utilize those loopholes — it certainly never should, which would potentially put it in violation of the convention."
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