More video footage is emerging of what Syrian rebels claim to be evidence of increasing government attacks.
Although the material cannot be verified, the intense scale of fighting is clear according to the medical charity, Doctors without Borders.
Its medics say they have been treating more wounds from tank and aircraft bombardment. They also claim to be seeing more injuries from heavy artillery than at any other time during the 17-month old conflict.
Opposition sources said anti-government forces have made strategically important gains after a week of heavy fighting on the Iraqi border.
Meanwhile, thousands of refugees trying to flee fighting have entered Turkey over the past 24 hours. Some 2,500 people, mostly from Idlib and Aleppo, have crossed the border, one of the highest daily refugee flows of recent weeks.