Fighting raged across Syria and air raids struck near Damascus and in the north on Saturday after a ceasefire declared for a Muslim holiday collapsed, with at least 221 people killed since it was due to take effect.
The truce for the Eid al-Adha holiday that started Friday -- conditionally agreed by the regime and the rebel Free Syrian Army (FSA) -- had raised the prospect of the first real halt to the fighting after 19 months of conflict.
But after fresh fighting on both Friday and Saturday, rebels and a monitoring group declared the ceasefire well and truly dead.
As clashes between President Bashar al-Assad's forces and rebels continued, a Syrian warplane struck a building in a rebel-held area east of Damascus that has been the scene of heavy fighting for weeks, killing eight.
"This was the first fighter jet air strike since the declaration" of a truce for the four-day holiday, the Syrian Observatory for Human Rights said.
"The truce is dead," the group's director Rami Abdel Rahman commented. "We can no longer talk of a truce."
Another air strike hit near the Wadi Deif military base in the northwestern province of Idlib, where rebels have been battling to take the facility, the group said.
A rebel commander in the northern city of Aleppo said there was no doubt the ceasefire initiative, proposed by UN-Arab League envoy Lakhdar Brahimi, had collapsed.
"This is a failure for Brahimi. This initiative was dead before it started," Abdel Jabbar al-Okaidi, head of the FSA military council in Aleppo, told AFP by telephone.
He insisted the FSA had not broken the ceasefire and was only carrying out defensive actions.
"I was on several fronts yesterday and the army did not stop shelling," Okaidi said. "Our mission is to defend the people, it is not us who are attacking."
But the army accused rebels of committing increasing violations and vowed to respond.
"For the second day, terrorist groups continued to flagrantly violate the ceasefire announced and respected by the army command," the military said in a statement on state television.
"The army will continue to track this increase of violations... and fight back against these criminal acts."
Foreign ministry spokesman Jihad Maqdisi said the army was committed to the truce, blaming rebels for provoking a response.
"The Syrian government is still completely committed to stopping military operations," he told AFP by email.
"But the violations that were committed were a consequence of attacks staged mostly by (rebel) groups that from the beginning refused the ceasefire, as shown by their official statements," Maqdisi added.
"We have documented the violations and sent messages to the UN Security Council," he said.
The Eid holiday began on Friday with a slowdown in the fighting -- and state television footage of Assad smiling and chatting with worshippers at a Damascus mosque -- but quickly degenerated.
The Observatory said 146 people were killed nationwide on Friday: 53 civilians, 50 rebels and 43 members of Assad's forces.
On Saturday, at least another 75 people were killed, it said, citing violence in Damascus province, Aleppo, Idlib, Daraa in the south and the eastern city of Deir Ezzor.
According to the Observatory, more than 35,000 people have been killed in the conflict, which began as an anti-regime uprising but is now a civil war pitting mainly Sunni rebels against Assad's regime dominated by his minority Alawite sect, an offshoot of Shiite Islam.
The Britain-based Observatory relies on a countrywide network of activists, lawyers and medics in civilian and military hospitals. It says its tolls take into account civilian, military, and rebel casualties.
Assad's forces and the FSA had both agreed to a call by Brahimi to lay down their arms for the Eid, but both also reserved the right to respond to attacks.
Okaidi said the ceasefire had been doomed from the start and that the international community needed to stop putting faith in the regime.
"The Syrian people have become guinea pigs. Every time there is an envoy who tries an initiative, while we know the regime will not respect it."
Observers also raised concerns of a new front in the conflict after reports that clashes between rebels and Kurdish militia on Friday left 30 dead and some 200 captured.
The fighting between rebels and the Kurdish Democratic Union Party (PYD), the Syrian branch of the Kurdistan Workers' Party (PKK), took place in the majority Kurdish neighbourhood of Ashrafiyeh in Aleppo, the Observatory said.