Members of the Free Syrian Army fired shoulder-mounted rockets and machine guns at a large Air Force Intelligence complex situated on the northern edge of the capital on the Damascus-Aleppo highway at about 2:30 a.m. (0030 GMT).
A gunfight ensued and helicopters circled the area, the sources said. The attack appeared to mark an escalation in armed confrontations between government and opposition forces instead of clashes involving street protesters.
“I heard several explosions, the sound of machine gun fire being exchanged,” said a resident of the suburb of Harasta, who declined to be named.
There was no immediate report of casualties and the area where the fighting occurred remained inaccessible, the sources said.
Syria said it would boycott an Arab League meeting following the body’s decision to suspend Damascus from the organization, as regional states stepped up efforts to isolate Assad for refusing to end the government repression of eight months of protests.
The meeting of Arab foreign ministers in Rabat on Wednesday comes four days after they decided to discipline Syria for pursuing the crackdown instead of implementing an Arab peace initiative.
The League has stopped short of calling for Assad’s departure or proposing any Libya-style military intervention.
“In light of statements by officials in Morocco, Syria has decided not to participate in the Arab meeting in Rabat,” the agency said, without giving details.
Morocco’s foreign minister said “Syrian colleagues” were welcome at the meeting but did not say if Syria’s foreign minister could attend.
Syrian forces killed at least six civilians on Tuesday, shooting from roadblocks in the northwestern province of Idlib and in raids on the central city of Homs and its environs, activists said. Several deaths also were reported in fighting between army defectors and loyalist forces on both sides.
The Syrian Observatory for Human Rights said the bodies of three young activists who were killed in custody were delivered to their families on Tuesday, including 23-year-old Osama Al-Sheikh Youssef.
“The family collected the body from Tishreen Military Hospital on the condition of a quiet burial. Security police in plainclothes stood on top of Osama watching as we lowered him into the ground,” an activist who attended the funeral said.
Syrian authorities have banned most independent media. They blame the unrest on “armed terrorist gangs” and foreign-backed militants whom they say have killed 1,100 soldiers and police. The United Nations say the crackdown has killed 3,500 people.
With armed resistance mounting against Assad’s rule, alongside mostly peaceful protests, hundreds of Syrians have been killed this month in one of the bloodiest periods of the revolt, inspired by uprisings which have overthrown leaders in Tunisia, Egypt and Libya.
An Arab official, who did not want to be named, said insurgent attacks on loyalist forces rose sharply in the last 10 days, although the army remains largely cohesive.
Tank bombardment continued overnight on Bab Amro, an area of Homs that has seen regular protests against Assad and where army deserters have been fighting loyalist forces, witnesses said.
“The tanks were firing according to instructions they were receiving from snipers stationed on rooftops,” a retired army officer in his 50s, who had fled the district, said.
As the diplomatic pressure rose, Syria released more than 1,000 prisoners, state media reported, including prominent dissident Kamal Labwani.
Human rights campaigners say tens of thousands of Syrians have been detained since street protests against Assad’s repressive rule erupted in March.
The Arab League, stung into action by months of bloodshed in Syria, met opponents of Assad on Tuesday, a day after violence in his country killed 69 more people. In a rare move among Arab leaders, Jordan’s King Abdallah said earlier this week that Assad should step down in the best interests of the country.
Prince Turki Al-Faisal, the former chief of the Kingdom's intelligence, said Assad’s “lack of response” to efforts to end the violence has made his departure inevitable, predicting that opposition to him will mount.
“I think it is inevitable that he will have to step down in one form or another,” said the Prince said in Washington.
The League voted to suspend Syria’s membership from Wednesday, and asked Syrian opposition groups to draw up plans for a transition of power, as a prelude to a wider gathering on Syria’s future planned by the Cairo-based body.
Arab ostracism is a particularly bitter blow for Assad, who has always seen himself as a champion of Arab unity. Damascus says it is committed to the Arab peace initiative, which calls for a cease-fire and dialogue with the opposition.
Syria requested an emergency Arab summit, but the Gulf Cooperating Council, a Saudi-led bloc of six Gulf Arab states, rejected the idea.
The United States hoped the League would use Wednesday’s meeting to send a “forceful message to Assad that he needs to allow for a democratic transition to take place and end the violence against his own people,” State Department spokesman Mark Toner said.
UN Secretary-General Ban Ki-moon said: “President Bashar should stop immediately the killing of his own people.”
Russia, one of Syria’s last few foreign friends, hosted talks with the Syrian National Council and urged it to hold a dialogue with Assad’s government. The opposition group responded by pressing Moscow to join calls for the Syrian leader to quit.
Russia joined China last month to block a UN Security Council resolution that would have condemned Assad’s crackdown, and has accused the West of discouraging dialogue in Syria.
