The International Red Cross is to attempt to deliver aid to the devastated Baba Amr district of the Syrian city of Homs for a third day.
A spokesman said the Red Cross would resume negotiations with officials who barred its convoy on Saturday.Syrian authorities had said the area was being cleared of booby traps.
Meanwhile, the bodies of a US journalist and a French photographer, who were killed in Homs, are due to arrive in Paris on Sunday morning.
The bodies of Remi Ochlik and Marie Colvin had been put on an Air France flight from Damascus on Saturday evening, France's ambassador to Syria Eric Chevallier told the AFP news agency.Their bodies had been handed over to diplomats earlier at the Al-Assad University Hospital in Damascus, reports said.
'Parlous state' The seven-lorry Red Cross aid convoy spent a second night in Homs after being blocked from entering Baba Amr on Saturday, despite having been initially given permission from the government.
"Any wounded in there who haven't already been helped by the Syrian government forces would be in a parlous state, perhaps they've already been brought out," said the UK spokesman of the ICRC, Sean Maguire.
"We really don't know how many people are still in there. It's all a bit of a mystery to us."
Mr Maguire said the ICRC had been "disappointed" not to be able to enter Baba Amr for two days running.
The BBC's Jim Muir, in neighbouring Lebanon, says the reason being given by the Syrian authorities for preventing access is that there are mines and potential booby traps in Baba Amr that need to be cleared first.
But he says there have been unconfirmed reports of revenge killings and summary executions by Syrian forces in Baba Amr and opposition activists believe the delay is to cover this up.
The reports speak of mass arrests of males over the age of 11, with the local cooperative building being turned into a detention centre.
One report alleged that a lorryload of dead bodies from Baba Amr was seen on a nearby highway. There were also reports of explosions and shootings in other nearby districts to which many families from Baba Amr had fled.
Activists also reported renewed shelling in other parts of Homs on Saturday.
Syrian state television has broadcast pictures from inside Baba Amr that show massive destruction, which it blamed on "armed terrorist gangs" carrying out a foreign plot to undermine Syrian stability.
Conditions in Baba Amr are said to be terrible, with no power and little food, water and medical supplies.
Our correspondent says the TV pictures showed nobody at all on the streets and that until the Red Cross gains access to make an assessment it will be impossible to say how many people remain.
'Disproportionate force'
In an address to the UN General Assembly on Friday, Secretary-General Ban Ki-moon said the international community had failed in its duty, and inaction had encouraged Syria's leaders in their repression of civilians.Mr Ban said it was time for the international community to speak with one voice.
"Continued division emboldens the Syrian authorities in their violent path," he said.
Meanwhile Paul Conroy, a Sunday Times photographer who fled Syria after being wounded in Homs, told the BBC that what was happening in Baba Amr was "systematic slaughter".
Mr Conroy, who was smuggled out of Syria into Lebanon on Tuesday, described the scenes in Homs from his hospital bed in the UK.
"I've done a fair few wars, I've never seen anything on this level," he said.
