The news came after security forces fired on a crowd of thousands of protesters in the city of Homs.

The demonstrators had gathered to call for the fall of the regime just hours after the authorities said they would suppress any “armed revolt” in the country.

One activist described the security forces as “swarming” into Al-Saa Square early on Tuesday morning, where some 20,000 people were staging a mass sit-in, insisting they would not leave until President Bashar al-Assad stepped down.

The shootings caused the protesters to scatter.