Syria has vowed to suppress an "armed revolt" undermining security in the country as protests spread and demonstrators clamoured for more democratic reforms.
The interior ministry issued the warning as thousands of protesters dug in at a main square in the central city of Homs, vowing to stay put until their demands are met.
"The latest incidents have shown that ... armed Salafist groups, particularly in the cities of Homs and Banias, have openly called for armed revolt," said a ministry statement carried by the official SANA news agency.
It accused such groups of killing soldiers, policemen and civilians, and of attacking public and private property, and warned that "their terrorist activities will not be tolerated".
The authorities "will act with determination to impose security and stability in the country" and will "pursue the terrorists wherever they are in order to bring them to justice and end the armed revolt," it said.
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The US called for Syria's Bashar al-Assad to "address the legitimate aspirations of its people" in the wake of 11 deaths at the hands of security forces during protests.
The US is "very concerned ... about the Assad regime," State Department spokesman Mark Toner told reporters.
Assad, he said, is facing "a push by his very own people to move in a more democratic direction", adding that the regime "needs to address the legitimate aspirations of its people".
Activists reported that more than 20,000 demonstrators erected tents in the main square of Homs a day after 11 people were killed by security forces in the city and a nearby town during a day of massive nationwide protest.
Syria has been rocked by deadly demonstrations since Saturday when President al-Assad vowed to lift nearly five decades of draconian emergency law -- a promise activists say is not enough.
"More than 20,000 people are taking part in the sit-in at Al-Saa Square (Clock Square) and we have renamed it Tahrir Square like the one in Cairo," rights activist Najati Tayyara told AFP from Homs.
The protesters put up tents in the square, copying demonstrators in Egypt who forced out veteran president Hosni Mubarak in February after 18 days of protests in Cairo's emblematic Tahrir Square.
"It is an open-ended sit-in which will continue until all our demands are satisfied," Tayyara said.
"This despotic regime must change. We have been waiting for 11 years for reforms," said Tayyara of the 11-year rule of Assad, who succeeded his autocratic father Hafez following his death in 2000. Protesters in Al-Saa Square chanted "sit-in, sit-in until the fall of the regime," and "Freedom, Freedom".
The people are demanding greater freedoms, the release from jail of all political prisoners and an end to arbitrary arrests on political grounds, he said.
"The young people are ready to face anything, including martyrdom." Noora told AFP of the sit-in: "All of Homs is here."
"We are all Syrians calling for liberty and the official Syrian media is lying by saying that foreign intruders are among us to spark violence.
The sit-in will go on until our demands for justice and liberty are met."
The embattled Assad, facing unprecedented popular protests since March 15, vowed on Saturday to lift the emergency law imposed by the ruling Baath Party when it seized power in 1963.
His pledge to end martial law to a new government tasked with implementing reform was deemed insufficient by activists who also want an end to the iron-fisted rule of the Baath party.
At least seven people were killed Sunday in Homs and four others died in the nearby town of Talbisseh when security forces opened fire on protesters and a funeral respectively, activists said.
A sea of mourners swamped Homs on Monday, carrying shoulder-high above the crowds seven coffins, some open, and others covered with Syrian flags.
Many mourners, clapping their hands, called for "the fall of the regime" and "freedom" as they paid tribute to the "martyrs," activists said.
The Homs sit-in started with a group of 3,000 people but swelled to 10,000 by late afternoon and twice as many in the evening.
Anger has swept through Homs since the announcement on Saturday that a Muslim cleric, Sheikh Faraj Abu Mussa, who was arrested a week earlier had died in custody.
