UN Secretary-General Ban Ki-moon says the Syrian crisis is "extremely dangerous" and could have massive repercussions globally.
Ban's comments came as UN Security Council members are considering a nonbinding statement calling on the Syrian government and opposition to implement proposals by UN-Arab League envoy Kofi Annan to end the violence.
If no objections by Security Council members are raised, diplomats say the statement will be considered approved.
Russia -- which along with China blocked two previous resolutions on Syria -- said it was ready to back a resolution supporting Annan's efforts.
But Moscow said it will not accept ultimatums to the Syrian government, a Moscow ally.
The UN says more than 8,000 people have been killed during the yearlong Syrian uprising.
Meanwhile, Syrian government troops are reported to be using tanks, artillery, and antiaircraft guns to fire into the Damascus' suburbs of Harasta and Irbin, which have been under rebel control for some two months.
Fighting between government and opposition forces in Damascus on March 20 killed at least 30 people.
With Reuters, AFP, and AP reports