British Prime Minister David Cameron has joined President Barack Obama in warning Syria the use of chemical weapons would trigger a re-think in their approach.
The rise in western rhetoric came as unverified footage showed Syrian tanks on the streets of Damascus.
Opposition activists reported 40 people were killed in bombardments timed with the departure of the United Nations observer mission.
Heavy shelling has also continued in suburbs across Aleppo as both regime forces and Syria rebels claim to be gaining ground.
The plight of civilians remains the focus for the UN's Emergency Relief Coordinator, Valerie Amos:
"The humanitarian situation has worsened since my visit in March. The most urgent and growing needs are for health care, shelter, food, water and sanitation. There are serious public health issues in the school buildings that are being used as shelters."
In such a school, those taking refuge blame the president for their plight. More than 500 families have fled the fighting in nearby Aleppo and no one knows when they will be able to return home.
Source: Euronews
