WASHINGTON: The reported torture of a Syrian boy shows the “total collapse” of Syrian authorities' willingness to listen to anti-government protesters, US Secretary of State Hillary Clinton said on Tuesday.

In some of her harshest comments about Syria's crackdown on the protests, Clinton suggested the Assad government's hold on power was weakening, while a US spokesman described the 13-year-old boy's reported treatment as “horrifying” and “appalling.”

The New York Times reported on Monday that an online video showed a 13-year-old boy, arrested at a protest on April 29, who it said had been tortured, mutilated and killed before his body was returned to his family.

“I can only hope that this child did not die in vain but that the Syrian government will end the brutality and begin a transition to real democracy,” Clinton told a news conference.

Syrian President Bashar al-Assad has sought to crush 10 weeks of protests against his 11-year reign with a military crackdown in which rights campaigners say 1,000 civilians have been killed and more than 10,000 people arrested.

Clinton said she was “very concerned” by reports about the 13-year-old boy, whom she identified as Hamza Ali al-Khateeb.

“I think what that symbolizes for many Syrians is the total collapse of any effort by the Syrian government's to work with and listen to their own people,” Clinton said, appearing with Colombia's visiting foreign minister.

“Every day that goes by the position of the government becomes less tenable and the demands of the Syrian people for change only grow stronger,” Clinton said.

“President Assad has a choice, and every day that goes by the choice is made by default.

He has not called an end to the violence against his own people, and he has not engaged seriously in any kind of reform efforts,” she added.

Activists said at least five people were killed on Tuesday when tanks shelled the central town of Rastan and security forces stormed Hirak, a town in the southern Hauran Plain where the uprising first broke out in mid-March.

Syria blames the violence on armed groups, Islamists and foreign agitators, saying more than 120 police and soldiers have been killed in the unrest nationwide.

Syrian state television said Assad had issued a “general amnesty” for all members of political parties but the United States dismissed this, as it has other moves such as his lifting of a state of emergency, as talk without action.

“He has talked reform but we have seen very little in the way of action,” State Department spokesman Mark Toner said at his daily briefing. “He needs to take steps -concrete steps, not rhetoric - to address what is going on in the country.