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, AFP reported.
At least 221 people have been killed since the ceasefire was due to take effect, the report said.
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 told AFP.
"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."
The army, however, 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.