The UNSC meeting comes as civilians in Syria's eastern Ghouta shunned Russia's offer to quit the besieged enclave for a second day, as opposition forces and Moscow blamed each other for the humanitarian deadlock.
Russia and Syria clashed with the US and its Western allies Wednesday over responsibility for the failure of a ceasefire to take hold in Syria as the UN said humanitarian convoys are ready to head to 10 locations including besieged eastern Ghouta near the capital Damascus.
The contentious Security Council meeting four days after members adopted a resolution demanding a ceasefire "without delay" for at least 30 days throughout Syria to deliver humanitarian aid and evacuate the critically ill and wounded reflected frustration and anger on both sides at the continued fighting and bombing.
UN humanitarian chief Mark Lowcock asked council members: "When will your resolution be implemented?"
TRT World's Frank Ucciardo reports from the UN headquarters in New York.
Aid delivery system "collapsed"
Lowcock said convoys are ready to go to 10 besieged and hard-to-reach locations including 45 trucks with aid for 90,000 people in Douma in eastern Ghouta. He said that since February 18 over 580 people are reported to have been killed and well over 1,000 injured in air and ground strikes in the Damascus, home to about 400,000 people.
Lowcock also warned that delivery of aid across conflict lines to millions of people in besieged and hard-to-reach areas throughout Syria "has totally collapsed."
"Unless this changes," he declared, "we will soon see even more people dying from starvation and disease than from the bombing and the shelling."
No civilians leave Ghouta
Russia has ordered a five-hour daily humanitarian pause to allow civilians to exit the region that started on Tuesday.
But no humanitarian aid has gone in and no civilians have left as the death toll tops 600 civilians in the last 10 days.
Residents said they do not trust the truce, and the UN and aid agencies criticised the unilateral arrangement, saying it gave no guarantees of safety for residents wishing to leave.
Regime forces, meanwhile, tried to push their way into the area, setting off ground battles.
Russian President Vladimir Putin blamed the opposition, saying they were preventing civilians from leaving the area known as eastern Ghouta and suggested Russia would not "endlessly tolerate" the situation there.
As TRT World 's Shamim Chowdhury reports, some residents are seeking refuge in underground shelters.
Regime offensive continues
The limited pause comes after a UN Security Council resolution that called for a nationwide 30-day cease-fire that failed to take hold.
While the relentless bombing has somewhat subsided in the region, home to around 400,000 civilians, the Syrian regime's push to squeeze the opposition groups out of the region continued.
The Syrian Observatory for Human Rights said regime shelling and limited clashes were reported on three fronts since the pause began: near Douma, in Harasta Farms, and near Shifouniyah.
The UN resolution came after hundreds of civilians were killed in eastern Ghouta and the region's medical facilities were targeted, overwhelming rescuers.
On the first day of the pause, activists reported around 20 civilians killed, including several pulled from under the rubble from previous bombings.
'Still there is no truce'
Bassam Abu Bashir, an anaesthetist in a hospital in eastern Ghouta, said the shelling continued on Tuesday and Wednesday but has largely spared his central hometown of Saqba and he had to deal with fewer injuries than in the past week.
He said the violence was now closer to the ground offensive areas. Abu Bashir said the shelling still struck civilians living in villages near the clashes.
"Even in areas that are calmer, there is still no truce. There are still jets flying over our heads and areas where there are gatherings that get targeted," Abu Bashir said.
"There are still injured coming in but not as many as before."
Eastern Ghouta, adjacent to the Syrian capital, came under opposition control in the early days of the regime crackdown on pro-democracy protests.
Under a siege since 2013, the region relied on tunnels and smuggling for supplies and movement.
But these tunnels have been controlled by the regime in the past months, tightening the siege on the region amid an escalating regime offensive.