The international community has come together in its condemnation of President Assad's regime following reports more than 200 civilians had been killed in a massacre in the village of Tremseh in Hama.
The killings were described by UN observers as "an extension of the SAAF's (Syrian Arab Air Force) operation in a mission report.
"The situation in Hama province continues to be highly volatile and unpredictable," the so-called "flash report" from the observer mission said.
"SAAF forces continue to target populated urban areas north of Hama City in a large scale."
There were no independent accounts of the number of dead or how they were killed.
Tonight UN observers said they were unable to access the targeted village.
The US Secretary of State Hilary Clinton said she is "outraged" by the massacre reports. She says reports indicate President Assad's government has deliberately murdered innocent civilians.
Clinton called for an immediate ceasefire around Hama to allow UN observers access and added that the perpetrators would be held accountable.
You may find some images in John Ray's report distressing:
Foreign Secretary William Hague also said he was appalled by the the atrocity. He offered his condolences to the victims and their families.
UN Secretary-General Ban Ki-moon has said the killings cast "serious doubts" on Syrian President Bashar al-Assad's commitment to a UN-backed peace plan.
"I condemn, in the strongest possible terms, the indiscriminate use of heavy artillery and shelling of populated areas, including by firing from helicopters," Ban said in a statement.
"They also cast serious doubts on President al-Assad's recent expression of commitment to the six-point plan in his meeting with the Joint Special Envoy," he said, referring to Assad's meeting with international envoy Kofi Annan in Damascus on Monday.
International mediator Kofi Annan has told the UN Security Council the latest developments in Syria showed UN resolutions were being ignored, making it imperative to send a message that there will be consequences.
In a letter to the Security Council, Annan repeated that the Syrian government's use of artillery, tanks and helicopters against the village of Tremseh violated its commitments under a UN-approved peace plan.
"Tragically, we now have another grim reminder that the Council's resolutions continue to be flouted...This is imperative and could not be more urgent in light of unfolding events," his letter said.