Harper had separate phone conversations Saturday with British Prime Minister David Cameron and French President Francois Hollande.
Officials in the Prime Minister's Office say the three leaders shared their concern about the accusations that the government of President Bashar Assad used chemical weapons on civilians.
The Syrian government has denied using chemical weapons and has pointed the finger at rebel forces.
Harper's aides say the leaders expressed a desire to get a clear picture of what happened as soon as possible.
The G20 summit in Russia next month was also discussed in both phone calls, according to the PMO.
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