The Syrian government launched a record 60 airstrikes on Monday, rebels said.
Anti regime activists said it was the highest number of assaults from the air since the conflict began 19 months ago.
The Syrian military attacked a number of rebel targets across the country, including the capital Damascus.
Eighty people were killed, including at least ten in a car bomb in the Syrian capital.
Yesterday marked the end of a four-day UN-backed truce to coincide with the Muslim holiday of Eid during which at least 500 people lost their lives.
The UN and Arab League peace envoy Lakhdar Brahimi condemned the ceasefire’s failure and said the crisis was “going from bad to worse.”
That was a view echoed by UN Secretary General Ban ki-Moon during a visit to his native South Korea earlier today.
Ban told MPs in Seoul that he wanted Syria’s leaders “to work together to immediately stop the violence” and turn to dialogue.
The UN chief also warned that those guilty of war crimes or crimes against humanity would face prosecution.