Syrian forces encircling the city of Homs have issued a 72-hour ultimatum for all protests against President Bashar al-Assad to stop, or a new offensive will begin.
The warning came as the regime's troops massed outside the city, apparently preparing for a major operation.
Homs has been a centre of unrest since the beginning of demonstrations against Mr Assad in March. The biggest protests have traditionally taken place on Fridays, the day of prayer in the Muslim world, when the mosques fill with worshippers.
This time, the security forces tried to curb the unrest by issuing an explicit threat. "We have been given 72 hours to stop protesting, or they are going to hit us hard," said an opposition activist in Homs going by the name Abu Rami.
Nonetheless, demonstrations swept across the city after prayers. People filled the streets, chanting "Syria wants freedom" and "Bashar is an enemy of humanity".
Witnesses said the security forces responded with violence, firing live rounds at some crowds. By last night, the Syrian Observatory for Human Rights, a London-based group, estimated that up to 10 people -- including two children -- had been killed in Homs.
Abu Rami said the security forces were "going mad in Homs", adding: "They are shooting everything, especially at people going outside from the mosques."
More fighting broke out between the Free Syrian Army, a rebel movement with a strong presence in Homs, and the regime's forces. An opposition activist reported "heavy gunfire and explosions" in the neighbourhood of Karm as-Zeitoun, adding: "Our fighters are trying to protect the protesters."
The Syrian National Council, an alliance of opposition parties, claimed in a statement that the forces outside Homs were preparing a "massacre".
They have resorted to new and increasingly violent tactics to deter civilians from joining the street protests, according to witnesses. A network of checkpoints has been established across Homs to pen in the demonstrators. At one roundabout, armoured vehicles had "made a checkpoint and are shooting randomly", said an activist calling himself Waleed.
Video footage showed the corpse of an eight-year-old boy, Mahar al-Huseini, lying on a couch in his home, blood pouring from a bullet wound to the head. He had been playing inside the house when a bullet entered through the window.
The regime has tried to seal off the districts of Homs most affected by protests, severing electricity supplies and communications. Some areas have been surrounded by newly dug trenches.
Some protests also took place in the suburbs of the capital, Damascus, according to activists. In the suburb of Kafr Batna, security forces are reported to have opened fire on civilians.
At least 24 people were killed across the country yesterday, adding to the UN's estimate of more than 4,000 since protests began in March. (© Daily Telegraph, London)