At least two rocket-propelled grenades hit a building belonging to the ruling Baath party in Damascus on Sunday, residents said, in the first insurgent attack reported inside the Syrian capital since an eight-month uprising began against President Bashar Assad.
"Security police blocked off the square where the Baath's Damascus branch is located. But I saw smoke rising from the building and fire trucks around it," one witness, who declined to be named, told Reuters.
"The attack was just before dawn and the building was mostly empty. It seems to have been intended as a message to the regime," he said.
The Syrian Free Army, comprised of army defectors and based in neighboring Turkey, claimed responsibility for the attack, just as Assad vowed in an interview to crush the insurgency and pursue a crackdown on protests demanding his removal that has killed 3,500 people, by a U.N. count.
The attack could not be independently confirmed. Syrian authorities have barred most independent journalists from entering the country.Story: Syria's Assad vows to continue crackdown despite Arab League pressure
The Local Coordination Committees activist network and several residents reported several explosions in the district of Mazraa in the heart of the Syrian capital.
The LCC said in a statement that the building had been hit at daybreak Sunday by several rocket-propelled grenades and that two fire brigades headed toward the area amid heavy security presence.
However, eyewitnesses said the building looked intact Sunday.
Residents in the Syrian capital said they heard two loud explosions but could not confirm whether the building had been hit.
"I woke up to the sound of two loud thuds," said a resident of the area who asked that he remain anonymous for fear of reprisals.
Damascus-based journalist Thabet Salem, who lives about 1100 yards away from the Baath party building and heard the explosions, said if the reports are confirmed, it would signal a new phase in the Syrian uprising.
"It would be an escalation that gives a new dimension to the whole situation," he said.
Syria's uprising against Assad has grown more violent and militarized in recent weeks, as frustrated protesters see the limits of peaceful action.Why Syria’s revolution needs a Benghazi
Army dissidents who sided with the protests have also grown more bold, fighting back against regime forces and even assaulting military bases.
The so called Free Syrian Army group of dissident soldiers this week staged their boldest operation yet, attacking a military intelligence building in a Damascus suburb .
Assad, who inherited power from his father in 2000, is a member of the Alawite minority community, an offshoot of Shiite Islam that dominates the state, the army and security apparatus in the majority Sunni Muslim country of 20 million.
The Syrian Free Army said in a statement Sunday's attack came in response to the authorities' refusal to release tens of thousands of political prisoners and pull the military out of restive cities in accordance with a plan agreed between the Arab League and Damascus.
An Arab League deadline for Syria to end its repression of the unrest passed with no sign of violence abating.Story: Russia warns Syria is close to 'real civil war'
The league on Sunday rejected a request by Damascus to amend plans to send a monitoring mission to Syria, Egypt's state news agency reported.
It said the league rebuffed Syria's approach in a letter from its Secretary-General Nabil Elaraby to Syria's foreign minister. The league wants to send a 500-strong mission of monitors to Syria to assess the situation there.
"The additions requested by the Syrian counterpart affect the heart of the protocol and fundamentally change the nature of the mission," the letter said, MENA reported, adding that the pan-Arab body rejected the demand.
The league had given Damascus three days from a meeting on November 16 to abide by a deal to withdraw military forces from restive cities and start talks between the government and opposition. The plan included sending an observer team to Syria.
The Arab League said in its statement that it was committed to an Arab solution for the Syrian violence and was working to end the crackdown on civilians in Syria.
In a surprise move, the league suspended Syria's membership last week.Video: Crisis accelerates in Syria (on this page)
Former Secretary of State Condoleezza Rice said Sunday that Assad was taking his country to the brink of civil war.
Rice told CNN's "State of the Union" that Assad's crackdown was creating a very dangerous situation.
She said Assad "is no friend of the United States" and that his overthrow would be a "great thing" for the Syrian people, U.S. interests and anyone seeking a more peaceful Middle East.
Rice was calling for the "toughest" possible penalties against Assad's government.
Meanwhile, activists in the central city of Homs said the body of Farzat Jarban, an activist who had been filming and broadcasting pro-democracy demonstrations in the city, was found dumped near a private hospital on Saturday with two bullet wounds.
"Security police are no longer just shooting protesters, they are targeting activists when they least suspect it, such as when they take their children to school. Sometimes they don't shoot to kill but to neutralize," said a doctor from Homs who has fled to Jordan.
"I treated an activist recently...They shot him in the thigh and by the time his family got him to me gangrene had spread and his leg needed to be amputated," he said.
Authorities blame the violence on foreign-backed armed groups which it says have killed some 1,100 soldiers and police.
Tanks and troops deployed in Homs after large anti-Assad protests six months ago. The authorities say they have since arrested dozens of "terrorists" in the city who have been killing civilians and planting bombs in public places.
The Syrian Observatory for Human Rights said security forces killed 16 civilians in raids and in shootings on protesters on Saturday, including two at a funeral in Kfar Tkharim in the northwestern Idlib province on the border with Turkey.
Non-Arab Turkey, once an ally of Assad's, is also taking an increasingly tough attitude to Damascus.Story: Assad's forces shell Syria villages for hours
Turkish newspapers said on Saturday Ankara had contingency plans to create no-fly or buffer zones to protect civilians in neighboring Syria if the bloodshed worsens.
Dissident colonel Riad al-Asaad, organizing defectors in Syria from his new base in southern Turkey, said in a television interview with Al Jazeera on Saturday that no foreign military intervention was needed other than providing a no-fly zone and weapons supplies.
He said more deserters would swell his Free Syrian Army's ranks if there were protected zones to which they could flee: "Soldiers and officers in the army are waiting for the right opportunity."
The dissident colonel denied government allegations that neighboring states were allowing arms smuggling into Syria. He said "not a single bullet" had been smuggled from abroad.
Weapons were brought by defectors, obtained in raids on the regular army or bought from arms dealers inside Syria, he said.
The Associated Press and Reuters contributed to this report.