The widow of an American soldier killed in Afghanistan and another former U.S. soldier partially blinded by a hand grenade plan to file an emergency injunction to stop Ottawa from paying $10.5-million to former child soldier Omar Khadr.

Tabitha Speer and Layne Morris allege Mr. Khadr was responsible for the death of Sergeant Christopher Speer and Mr. Morris's injuries in Afghanistan. Two sources say they are expected to ask the Ontario Superior Court as early as Wednesday to uphold a 2015 Utah civil court judgment ordering Mr. Khadr to pay them $134-million (U.S.) for his actions in Afghanistan.

"They are trying to get an emergency injunction in a Canadian court to have their award in the United States enforced in Canada," one source said. "Their desire is to have U.S. courts enforced in Canada, which would mean that any money that goes to Mr. Khadr would go to them."

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A federal official said the prospect of the courts ruling in their favour is remote.

Attempts to reach the U.S. lawyer for Ms. Speer and Mr. Morris were unsuccessful. Mr. Khadr's lawyer, Dennis Edney, said he was unaware of the injunction and would not discuss the $10.5-million (Canadian) compensation package. "I can't talk to you because that is the arrangement with the government," he said.

Mr. Edney has been seeking a formal apology and $20-million in compensation from the federal government for the alleged abuse and neglect that Mr. Khadr suffered while he was in the U.S. military prison at Guantanamo Bay, Cuba.

The Globe and Mail reported on Monday that the Trudeau government has agreed to offer an apology and $10.5-million compensation package to Mr. Khadr.

On Tuesday, the Opposition Conservative Party denounced the payment and urged Mr. Khadr to give the money to the Speer family.

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"Canadians know this is wrong," Conservative Leader Andrew Scheer said on Twitter. "If Omar Khadr is truly sorry for what he did, he'll give every cent to Tabitha Speer and her two children."

Mr. Khadr was accused of throwing a grenade that killed Sgt. Speer, a U.S. army medic, and blinded Mr. Morris in one of his eyes during a firefight between al-Qaeda militants and U.S. troops in 2002.

Mr. Khadr was 15 years old at the time and was blinded by shrapnel in one eye and suffered serious wounds to the shoulder and chest. He was flown to the U.S. detention facility for captured and suspected terrorists at Guantanamo.

As part of a plea deal in 2010, Mr. Khadr pleaded guilty to Sgt. Speer's murder and was returned to Canada in 2012, where he served time in a maximum-security prison before he was freed on bail in 2015. He later recanted that he had any role in killing Sgt. Speer.

Once the youngest detainee at Guantanamo, Mr. Khadr was subjected to sleep deprivation and solitary confinement by U.S. interrogators.

"If he [Mr. Khadr] has a cause for action, he should be suing the Americans. It should not be on the Canadian taxpayers to pay this payment," Conservative MP Tony Clement said.

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Pascal Paradis, executive director of Lawyers without Borders, said the Conservatives are off base with their opposition to federal compensation for Mr. Khadr.

"It is not a political matter. It is a legal matter," he said. "In this case, the Supreme Court of Canada has said not only once but twice that Canada was wrong in dealing with the Khadr case, that Canada had participated in violating his basic human rights, including participation of Canadian agents in interrogating Mr. Khadr knowing he had been subjected to cruel, inhumane and degrading treatment."

The Supreme Court of Canada ruled in 2010 that the actions of federal officials who participated in U.S. interrogations of Mr. Khadr had offended "the most basic Canadian standards about the treatment of detained youth suspects."

Prime Minister Justin Trudeau offered a vague response when asked about the compensation package for Mr. Khadr.

"There is a judicial process under way that has been under way for a number of years now and we are anticipating, like I think a number of people are, that that judicial process is coming to its conclusion," Mr. Trudeau said on Tuesday after a meeting in Dublin with Irish Prime Minister Leo Varadkar.

The office of Public Safety Minister Ralph Goodale was equally circumspect.

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"Settlement processes are always strictly confidential by nature. Accordingly, the government is not in a position to provide any further comment one way or another," Mr. Goodale's office said in a statement.

Mr. Goodale and Foreign Affairs Minister Chrystia Freeland are the lead ministers on the Khadr file.

There was wide-spread criticism of the multimillion-dollar compensation package on social media, particularly from Conservatives and their supporters.

Former Conservative defence minister Jason Kenney, now the Leader of Alberta's Progressive Conservative Party, called the payment "odious" on Twitter: "Confessed terrorist who assembled & planted the same kind of IEDs [improvised explosive devices] that killed 97 Canadians to be given $10-million," Mr. Kenney tweeted. "Khadr confessed to murdering Christopher Speer, a medic who rushed to his aid. Speer's family won a $134-million judgment against Khadr."

Stephen Harper's former campaign manager, Jenni Byrne, also weighed in on Twitter, as did many other Canadians.

"He wasn't 'accused' of war crimes & killing U.S. army medic Christopher Speer – he plead [sic] guilty!" Ms. Byrne tweeted.

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Mr. Edney said Mr. Khadr was groomed into fighting by his radical father, Ahmed Said Khadr – a top al-Qaeda operative until he was killed in a gunfight with Pakistani troops in 2003.

Mr. Khadr apologized to the families of the victims when he was released from prison in 2015. He said he rejects violent jihad and wants a fresh start to finish his education and work in health care.

In March, Mr. Khadr underwent a 19-hour operation in an Edmonton hospital to repair his shoulder, which was severely damaged during the firefight with U.S soldiers.

"The fact that he is living in Canada at liberty should be compensation enough. After all, he is former enemy terrorist combatant," Conservative foreign affairs critic Peter Kent told The Globe.

With files from Steven Chase and Paul Waldie