At least 19 people were killed in air strikes launched by Syrian regime against opposition forces in several areas in the northern Syrian city of Aleppo, the Britain-based monitoring group Syrian Observatory for Human Rights (SOHR) said on Friday.
The watchdog said the death toll is expected to rise with dozens more wounded, some of them seriously.
The attack is not the first one in this week. On Tuesday, 50 civilians including two children were killed in the air strikes which were carried out by Syrian regime in Maarat al Numan and Kafr Nubl, the two northwestern Syrian towns located in Idlib Province.
Friday's attack came a day after Syrian opposition delegation High Negotiations Committee (HNC) announced that they will leave Geneva by Friday saying that their demands relating to the military operations on the ground in Syria have yet to be met.
Mohammad Alloush, one of the negotiators in the opposition delegation, said on Thursday He [Bashar Assad] must stop the massacres he is committing everyday, so he can be a human with an ounce of nationalism. Then maybe the negotiations will resume.
A cessation of hostilities deal, brokered by the United States and Russia in February, initially reduced violence in the western portion of the country, but has been strained by increased fighting around Aleppo, and in other areas of Syria.
Since the deal took effect on February 27, at least 614 civilians have been killed in the war-torn country, according to the London-based human rights group Syrian Network for Human Rights (SNHR).
Syria has been locked in a vicious civil war since early 2011, when the regime of Bashar al Assad cracked down on pro-democracy protests.
United Nations estimates that 400,000 people have been killed in the five-year-old war.