OTTAWA - Canada is "deeply disappointed" the Syrian government created a threatening environment for United Nations monitors who were forced to suspend work Saturday.

"The Syrian government has the obligation to protect the well-being of these monitors as they conduct their work, and report their findings," said Rick Roth, a spokesman for Foreign Affairs Minister John Baird.

"Anything less is a complete abdication of their responsibilities, and a clear signal to the international community that (Syrian president Bashar) Assad has no interest in co-operating."

Growing violence in Syria has forced UN observers to halt operations on the ground as global leaders prepare to meet for G20 talks this week.

Chief monitor General Robert Mood said increased bloodshed posed a threat to unarmed observers and prevented them from overseeing a ceasefire in the region.

Canada and other western allies have repeatedly condemned heightened violence along with Assad but partners haven't signalled interest in military intervention.

Russia and China, both permanent members of the UN Security Council with veto power, have backed Assad during 15 months of bloodshed.

US officials say President Barack Obama and Russian president Vladimir Putin will discuss the conflict in Syria at the G20 summit in Mexico next week.

- with files from Reuters