The evacuation of civilians from besieged areas of Homs city in Syria was set to resume on Wednesday as peace talks in Switzerland between the country's warring sides appeared deadlocked.
On Tuesday, Homs governor Talal Barazi announced evacuation and aid delivery operations would be suspended for a day over "logistical difficulties".
And the United Nations expressed concern about the fate of hundreds of boys and men held for questioning by Syrian authorities after being evacuated.
More than 1,000 men, women and children have been evacuated from besieged rebel-held parts of Homs since Friday, many fragile and malnourished after surviving for more than 18 months on dwindling food supplies.
"There are children there, and this is very heartbreaking, that this is the first time they see a banana," Syrian Red Crescent head of operations Khaled Erksoussi told AFP.
"Our psychological support teams are there to try to deal with the cases as they come out, but eventually the teams themselves will need psychological care because the situation is very emotional and passionate."
He said the Red Crescent was on standby to resume work Wednesday after a meeting between Barazi and UN representatives.
"We are expecting that we'll be able to get some more food material in and hoping to get some more people out," he said.
Red Crescent workers backed by UN agencies began evacuating some of the estimated 3,000 people trapped in besieged areas on Friday under a UN-mediated deal.
Just over 1,150 people have left since then and the World Food Programme has delivered enough food for another 1,550 families left behind.
The UN's refugee agency UNHCR said Tuesday that 336 boys and men aged 15 to 55 had been detained for questioning as they left, with just 42 subsequently released.
Activists have long expressed fears that the government would round up opposition fighters and other opponents.
The evacuations have also been marred by violence, despite a tenuous ceasefire, with shelling killing 14 people and aid convoys coming under fire.
'Chance won't come again'
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On Tuesday, operations ground to a complete halt because of what Barazi called "logistical" problems.
Erksoussi said there were particular difficulties finding a safe route out for a group of families in the Bustan al-Diwan district.
"They are about 28 families, most of them are Christians," he said.
"They want to get out but there is no road from where they are to the exit point, so we are pressuring the UN to put on pressure to provide a route for them to get to the exit point."
The operation has been welcomed internationally and is providing desperately needed relief for civilians who have described surviving on little more than olives and wild plants.
Erksoussi said the Red Crescent was eager to take advantage of any window for humanitarian relief.
"We will use any chance we get to get in and deliver aid and help people to leave because we believe this chance won't come again," he said.
In Geneva, meanwhile, talks were due to resume between regime and opposition delegations after a second day of meetings that left even UN-Arab League mediator Lakhdar Brahimi downbeat.
"We are not making much progress," he told reporters after chairing a face-to-face session with both sides.
The opposition delegation has already warned it will not attend a third round of talks if the current discussions do not produce real progress.
And in Damascus on Tuesday, Syria's National Reconciliation Minister Ali Haidar said he expected the talks "under the current circumstances, will end in failure".
The two sides disagree fundamentally on the purpose of the meetings, with the opposition insistent on the formation of a transitional government without President Bashar al-Assad.
The regime says Assad's future is non-negotiable and that the talks must focus on halting "terrorism", its term for those who oppose it.
The regime delegation also slammed the opposition for failing to acknowledge "terrorism" in Syria, including the killing of more than 40 people, half of them civilians, in an Alawite village.
The Syrian Observatory for Human Rights, an NGO, said 21 civilians and 20 pro-regime fighters were killed by Islamist rebels in the village of Maan on Sunday.
On Tuesday, UN Secretary General Ban Ki-moon expressed "great shock" over the reports, urging that "the perpetrators of this massacre, and all other crimes in Syria" be brought to justice.