UPDATE: Harrowing personal testimony about the alleged massacre has now emerged. The accounts are now included here.
The bodies of at least 26 children and 21 women were discovered in the ruins of the city, said to be victims of a massacre by government security forces.
The city has been subject to an assault by the Syrian army for weeks, and attacks have continued even after opposition forces withdrew under pressure from intense shelling.
The Activists News Association published extremely graphic videos on Facebook which appeared to show the corpses in a field hospital.
The latest gruesome discovery came as American reporter Marie Colvin, who died alongside French photographer Remi Ochlik in a mortar attack on Homs in February, was buried in New York.
Elsewhere British Foreign Secretary William Hague pushed the UN security council to adopt a resolution condemning the violence after a weekend of diplomatic efforts by UN and Arab League special envoy Kofi Annan did not lead to a hoped-for breakthrough.
Annan said that he was "optimistic" following the talks, and that if enacted his "concrete proposals" could lead to a ceasefire.
He added that every Syrian "wants peace".
Critics said that President Assad had rejected all talks with "armed terrorist groups", meaning the increasingly militarised opposition movement, and had given no ground over his own personal hold on power.
Assad said during the talks: "No political dialogue or political activity can succeed while there are armed terrorist groups operating and spreading chaos and instability."
Dr Bassma Kodmani, with the opposition Syrian National Council, told the BBC Assad had to stand down.
He said that Assad leaving office was a "first condition" of any negotiation.
Large-scale demonstrations against Assad's rule, including some in central Damscus were reported on Sunday evening, after a weekend of violence.
The UN says that at least 7,500 people have been killed since the start of the uprising 12 months ago.