The head of the UN Supervision Mission in Syria has told the UN Security Council of the intensifying violence but said the nearly 300 unarmed monitors were "morally obliged" to stay.
Major General Robert Mood said UN vehicles had been hit 10 times by "direct fire" and hundreds of times by "indirect fire." Nine UN vehicles had been hit in the past eight days alone.
UN peacekeeping chief Herve Ladsous said it had been decided to maintain the integrity of the mission for the time being.
The future of UNSMIS is being discussed as various diplomatic initiatives have been launched on Syria and the mission's current mandate ends on 20 July, Mr Ladsous added.
The use of improvised explosive devices (IEDs) and snipers has increased, causing many of the mounting casualties, Mood told the envoys as his team struggles to shore up a ceasefire supposed to take effect from 12 April.
But he insisted the suspension of operations did not mean an "abandonment" of Syria.
UNMIS was "morally obliged not to turn away" and "must redouble efforts," General Mood was quoted as saying.
The UN monitors are seeking to implement a six-point peace plan put together by UN-Arab League envoy Kofi Annan.
Russia resists western pressure on regime change
Meanwhile, Russia has again resisted Western pleas to help remove Syria's President Bashar Assad from power.
"We believe that nobody has the right to decide for other nations who should be in power and who should not," Russian President Vladimir Putin told reporters after the latest G20 summit in Mexico.
"It is not changing the regime that is important, but that after changing the regime, which should be done constitutionally, violence is stopped and peace comes to the country," he said.
US President Barack Obama said he told Mr Putin and Chinese President Hu Jintao on the sidelines of the summit that Mr Assad could no longer remain in power after the massacres of large numbers of civilians.
"I wouldn't suggest that at this point the US and the rest of the international community are aligned with Russia and China... but I do think they recognize the grave dangers of all out civil war," Mr Obama said.
France's President Francois Hollande, however, said Russia "is playing its role to permit a transition." He added: "Those who are massacring their people today cannot play a role in the future of Syria."
