A truce that has allowed the evacuation of hundreds of civilians from besieged districts of Syria's Homs was extended for three days but fresh peace talks in Switzerland bogged down Monday in mutual recriminations.
The extension of the tenuous truce in Homs came as around 450 civilians were given safe passage out of the war-ravaged city, according to Syria's Red Crescent, bringing the total number allowed out since Friday to some 1,200.
The evacuation of civilians from neighbourhoods where they had been trapped for nearly 18 months was marred by violence over the weekend, with 14 people killed in shelling that threatened to derail the humanitarian mission.
Footage distributed by activists showed scores of traumatised men, women and children making their way down a rubble-strewn road Monday flanked by rows of UN vehicles. One old woman lagged behind, alone.
In Geneva meanwhile, the warring sides blamed each other for escalating violence that has killed hundreds of people across the country in recent days, as they did throughout a previous round of talks in late January.
The Syrian opposition delegation warned it would not return for a third round if no progress was made in the current session.
"If there is no progress at all, I think it would be a waste of time to think about a third round," opposition spokesman Louay Safi told reporters late Monday.
UN and Arab League mediator Lakhdar Brahimi began the latest session in Geneva by shuttling between the two sides, and suggested in a letter that the parties wait until the second or third day to resume joint meetings.
Brahimi wrote that he hoped that "separate sessions can lead to some positive outcomes," and tried to nudge the teams towards discussion of how to stop the fighting and agree on a political transition.
Both sides said there would be a joint session on Tuesday, with the opposition saying it would begin at 10:00 am (0900 GMT).
The situation in Homs had been discussed at the previous round of talks held last month, but a breakthrough only came later.
Some 3,000 people had been trapped there by the army siege, surviving on little more than olives and wild herbs for months. Activists said new mothers were unable to breastfeed because of malnutrition.
On Saturday, the Red Crescent was able to deliver 250 food parcels, along with hygiene kits and medicine, despite its vehicles being fired upon. One driver was wounded.
Mortar fire was also reported during the delivery.
UN humanitarian chief Valerie Amos welcomed the three-day truce extension, which officials said included Monday and would expire Wednesday night, but said aid workers had witnessed "terrible conditions" in a field hospital there.
She pointed out that tens of thousands of Syrians are trapped in besieged areas across the country.
"I hope that those negotiating in Geneva agree to allow the sustained delivery of aid to the 250,000 people in besieged communities in Syria and all those who are in desperate need across Syria," she said in a statement.
The International Committee of the Red Cross and the World Food Programme (WFP) have also called for unimpeded access.
Homs, much of which has been reduced to rubble, was dubbed "the capital of the revolution" by activists before a bloody 2012 offensive by regime forces recaptured much of the city.
The regime imposed a tight blockade on the remaining rebel-held areas shortly thereafter.
Elsewhere in Syria clashes raged on several fronts, and on Sunday alone 400 people were killed across the country, according to the Syrian Observatory for Human Rights, a Britain-based group relying on activists and other witnesses inside the war-torn country.
In eastern Syria, rebels also fought the jihadist Islamic State of Iraq and the Levant (ISIL), where a new front opened over the weekend.
As the evacuation in Homs progressed Monday, another aid operation for the besieged Yarmuk Palestinian refugee camp in southern Damascus was suspended because of clashes between troops and rebels.
The UN agency for Palestinian refugees "is assured that the current suspension will be lifted soon, pending negotiations between government forces and groups inside Yarmuk," spokesman Chris Gunness said.
Some 20,000 Syrians and Palestinian refugees have been living under an army siege there since June 2013, and around 80 people have died from food and medical shortages, according to the Observatory.
Syrian state television meanwhile reported that "terrorists" had prevented the Red Crescent from delivering food and medicine to Aleppo's central prison for a fourth day.
It said the delay had led "to the deaths of 20 inmates from malnutrition and lack of medicine".
The Red Crescent could not immediately be reached for comment on the report.