At least six people have reportedly been killed in fresh fighting between Syrian rebels and government troops.
Deraa and Homs are said to have been heavily bombarded. According to the Syrian Observatory for Human Rights dozens of people have been injured.
There has also been a suicide attack in the majority Kurdish region for the first time in the conflict.
State television says four people died when the north-eastern city of Qamichli was hit by an enormous explosion. The target is thought to have been the security headquarters of the Kurdish region.
It comes after rebels launched a renewed offensive on Aleppo. On Saturday, a fire triggered by battles with government troops tore through the city’s souk, one of the best preserved bazaars in the Middle East.