The Syrian Observatory for Human Rights says the deaths of more than 6,600 people has made May the bloodiest month so far this year in Syria.
The monitoring group says the toll includes at least 1285 civilians, more than half of whom were killed in regime air raids.
The UN's Syria peace envoy Staffan de Mistura condemned government aerial bombardment of civilian areas over the weekend, calling it unacceptable.
Since it began in March 2011, Syria's conflict has left 220,000 people dead and forced millions to flee.
GAiN is helping provide relief to Syrians who are internally displaced. To find out more information, click here.