Amnesty International has urged the Syrian authorities to protect child protesters after fresh reports of young people being tortured and killed.
The globally respected human rights group says that video evidence has emerged of two new cases of teenagers dying after receiving injuries caused by beatings and gunshot wounds.
"Reports that the Syrian security forces have tortured and killed children in their custody would, if confirmed, mark a new low in their bloody repression of protests," said Philip Luther, Deputy Director of Amnesty's Middle East and North Africa Programme.
He continued: "The violent deaths suffered by Thamer al-Sahri and other children are utterly shocking, as is the Syrian authorities' apparent lack of action to rein in the security forces accused of being responsible for them."
International media released an amateur video on 8 June 2011 purportedly showing the body of 15-year-old Thamer al-Sahri, which was returned to his family in the Syrian village of Jeeza the day before. The body of al-Sahri, who disappeared on 29 April during a protest, is apparently punctured by bullet wounds and missing one eye and several teeth.
Thamer al-Sahri is the fourth child reported to have died in custody since March, according to Amnesty.
Protesters in Syria were galvanised by news of the death late last month of 13-year-old Hamza al-Khateeb. The boy went missing after a demonstration at an army barracks near the southern town of Deraa at the end of April 2011.
According to opposition activists, he was abducted and tortured to death by local security forces. They said his mutilated body was handed back to his family four weeks later.
The government, however, insists the boy received three fatal gunshot wounds during the protest and died on the spot, but there was a delay in handing over his body because he was not identified. A forensic specialist consulted by Amnesty said after analysing the video of his body that the boy was tortured with a blunt instrument and received two gunshot wounds.
On 8 June Amnesty International received a video clip showing the body of yet another individual, probably aged 18 or 19, showing evidence of brutal treatment. The organisation said some 32 children, aged between 12 and 17, remain in detention and could be at risk of torture.
Pro-democracy demonstrations began in Syria in mid-March this year, and have continued across the country, which has been ruled by the Baath Party since 1963. Protesters are demanding the ouster of al-Assad, who took over his father in 2000.
Amnesty International says it believes that at least 1,104 people have been killed in confrontations so far, including 82 children.