Canada is imposing additional sanctions on Syria, mounting more pressure on the Assad regime to stop attacks on civilians.

Foreign Affairs Minister Chrystia Freeland announced that 17 high-ranking officials in the government of President Bashar al-Assad and five organizations linked to the use of chemical weapons will be subject to an asset freeze and dealings prohibition.

"Canada is working with its allies to put an end to the war in Syria and to hold those responsible to account," Freeland said in a statement released Friday. "Today's announcement of additional sanctions against key officials in the Syrian regime sends a strong, unified message to the Assad regime that their war crimes will not be tolerated and that they will be held accountable for their actions."

Assad has denied his government is behind chemical attacks, calling the allegation "100 per cent fabrication."

Last Thursday, Canada announced sanctions against 27 officials in the Assad regime.

Freeland has urged Russia, a longtime supporter of Assad, to broker his departure and help negotiate a peaceful resolution to the conflict.

Last week Russia vetoed a UN resolution drafted by Britain to condemn the reported use of chemical weapons and demand a quick investigation.