Operations to evacuate civilians and deliver aid in besieged parts of Syria's Homs resumed Wednesday after being suspended a day earlier, as peace talks in Geneva appeared deadlocked.

But there was still no word on the fate of hundreds of boys and men detained for questioning by authorities after they were evacuated from the city.

"At 11:00 am (0900 GMT), food aid was able to enter the Old City of Homs," the provincial governor Talal Barazi told AFP.

"The vehicles that are taking in the aid will bring out a number of civilians, including 20 Christians from the Bustan al-Diwan neighbourhood," he added.

The Syrian Red Crescent tweeted pictures of its staff loading sacks of aid onto flat-bed trucks for transport into besieged parts of the city.

More than 1,000 men, women and children have been evacuated from besieged rebel-held parts of Homs since Friday, many weak 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."

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.

Despite the suspension of operations on Tuesday, more than 1,150 people have been evacuated since the operations began and the World Food Programme has delivered enough food for 1,550 families remaining inside.

Concern has grown, however, over the fate of 336 boys and men aged 15 to 55 who UN officials say were detained for questioning by authorities as they left Homs.

Just 42 have been released, according to UN figures, raising fears among activists that the regime is rounding up military-age men among those leaving.

Activists inside Homs said some men leaving had been prevented from going to areas of their choice, stripped of their ID cards and issued ID documents instead.

"There are some 60 activists in the besieged areas. Some of them want to leave, but will only do so if there are guarantees for their safety," said Yazan, an activist who asked that his full name not be published for fear of retribution.

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'

Erksoussi said there were particular difficulties finding a safe route out for a group of 28 families, mostly Christians, in the Bustan al-Diwan district.

"They want to get out but there is no road from where they are 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.

"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," Erksoussi 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 on Tuesday after chairing a face-to-face session with both sides.

The opposition warned it would not attend a third round of talks if no progress was made.

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 opposition insists on the formation of a transitional government without President Bashar al-Assad, but the regime says Assad's future is non-negotiable and that the talks must focus on halting "terrorism."

It says opposition fighters carried out a massacre in the Alawite village of Maan last week, where the Syrian Observatory for Human Rights, a Britain-based monitoring group, says Islamist rebels killed 21 civilians and 20 pro-regime fighters 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.