Tens of thousands of Syrians have taken to the streets across the country in defiance of continuing violence to demonstrate against the government of President Bashar al-Assad.
On Thursday at least 55 people died in two huge blasts in the capital, Damascus, and now there are reports of a large explosion in the northern city of Aleppo, hours after officials said they had foiled a car bomb attack there.
The blast is said to have happened near the local headquarters of the ruling Baath party.
Earlier, state television reported the death of a would-be bomber said to have had a 1200-kilogram device in his car.
Opposition figures have accused the Assad government of staging bomb attacks in an attempt to discredit them.