The bodies of 26 children and 21 women were found in the central city of Homs on Monday.
"Some of the children had been hit with blunt objects on their head, one little girl was mutilated and some women were raped before being killed," Homs rights activist Hadi Abdullah told Gulf News.
He described the bodies "some with their throats slit and others with stab wounds" that were found in the Karm al-Zaytoun and al-Adawiyeh neighborhoods.
Abdullah's report solidifies the number killed in Monday's widely reported massacre at 47 and confirms reports of reprisal operations in Homs by the Syrian regime.
The flashpoint protest city of Homs was shelled and under sniper fire by Syrian troops for 26 straight days that saw at least 700 civilians killed.
The shelling, which stopped on March 1 when rebel fighters from the Syria Free Army withdrew, was followed by what rights activists described as "mop up operations" by Syrian forces.
In the following week, during which aid workers and UN officials were barred from the city, rumors of systemic rape, torture, and summary executions circulated.
On March 8, UN aid chief Valerie Amos was allowed into Homs for a brief tour in the company of Syrian Red Crescent personnel, but shelling resumed over the weekend.
United Nations Secretary-General Ban Ki-moon urged President Bashar al-Assad to act within the "next few days" on UN-Arab League proposals.
"The Syrian government has failed to fulfill its responsibility to protect its own people and instead has subjected its citizens in several cities to military assault and disproportionate use of force," Ban said.
Meanwhile, former UN secretary general Kofi Annan, who is serving as the UN-Arab League envoy to Syria, finished a two-day meeting with Assad that produced no results.
Despite repeated calls for action and criticism of Assad's regime from UN leaders the world body remains deadlocked due to opposition from China and Russia in the Security Council.
Beijing and Moscow, which have billions of dollars of trade tied up with Damascus, have consistently vetoed resolutions calling for Assad's ouster, universal sanctions, or more aggressive action.
Russia has also dogmatically insisted it will continue to sell arms to Assad's regime, including sophisticated anti-aircraft systems that would make enforcing a no-fly zone over Syria difficult.
Western officials singled out Russia for sharp criticism saying Moscow is "paralyzing" the international community and giving Assad's "regime a license to kill."
Meanwhile, Syria said it would preemptively withdraw its ambassadors from Europe over fears EU members will expel them.
The US, Britain, Switzerland, Canada and France have already closed their embassies in Damascus.