The federal government wants officials in the Syrian regime who orchestrated a series of chemical weapons attacks on their own people to be prosecuted under international law.

The government also has called for ISIS militants who used mustard gas to be brought to justice.

"Canada calls for those responsible for the heinous use of chemical weapons to be held accountable for their actions and blatant violations of law," Foreign Minister Stéphane Dion said in a statement.

"The international community must hold the government of Syria to its obligations under the Chemical Weapons Convention, international humanitarian law and UN Security Council Resolution 2118 (2013)."

Dion issued the statement in response to an Aug. 24 United Nations report detailing the Syrian government's repeated use of chlorine gas against its own citizens.

The report also concludes that on at least one occasion ISIS used sulfur mustard, commonly known as mustard gas — in Marea, Syria, on Aug. 21, 2015.

"This serious, independent and neutral investigation clearly demonstrates that the government of Syria has repeatedly used chemical weapons against its own people and that Daesh used sulphur mustard," Dion said, referring to ISIS as Daesh, the Arabic acronym of the group's name.

In the statement, Dion goes on to call for the immediate end to the bombing of hospitals and the targeting of civilians with barrel bombs, chemical weapons and other "indiscriminate weapons" by both Syria and ISIS.

Limited investigation bears fruit

The report was the third from the Organization for the Prohibition of Chemical Weapons-United Nations Joint Investigative Mechanism, or JIM for short.

The task force reviewed more than 8,500 pages of documents, transcripts of 200 interviews, nearly 1,000 photographs, 450 videos, 300 pages of forensic analysis and another 3,500 files in reaching its conclusions.

The investigative unit was unable to compel either Syria or ISIS to provide any evidence and was limited by its inability to access "locations under investigation, owing to the dire security situation on the ground," the report said.

Despite those and other limitations, JIM was able to conclude in its report that the Syrian government used chlorine gas on a number of occasions.

On April 21, 2014, in Talmenes, Syria, a Syrian military helicopter dropped a device containing a toxic substance, poisoning large numbers of civilians.

On March 16, 2015, in Sarmin, Syria, a Syrian military helicopter dropped a device containing chlorine on a house, killing six people.

On March 24, 2015, in Binnish, Syria, a barrel bomb containing chlorine was used against civilians by the Syrian military.

Other incidents not confirmed

There were a number of other incidents in which JIM had good reason to believe that chemical weapons had been used against civilians by the Syrian regime, but the unit was unable to confirm definitively for a number of reasons. One of those reasons was the removal of bomb fragments at specific sites before evidence could be gathered.

According to a statement from Global Affairs, the federal government contributed $2.8 million to help fund JIM in February and supports an extension of its mandate so it can "complete its work."

Alex Neve, secretary general of Amnesty International Canada, welcomed Dion's call to bring Syria and ISIS to justice under international law to demonstrate that those committing war crimes cannot do so with impunity.

"One measure that Canada could and should champion is the need, long-ignored by the international community, for the situation in Syria to be referred to the International Criminal Court," Neve said. "That step can only be taken by the UN Security Council. Canada should press council members to do so."

Conservative defence critic James Bezan criticized Dion and Trudeau's government for withdrawing Canada's CF-18 fighter jets from the region, saying the UN report highlights the need for Canada to take a more active fighting role in Syria and Iraq.

"The Official Opposition is appalled by these reports," Bezan said in a statement. "‎It's deplorable that ISIS continues to brutalize its victims, now using chemical attacks as part of their arsenal in committing atrocities."