Two booby-trapped cars blew up at security sites in Damascus on Friday, killing a number of civilians and soldiers, state television said, in the worst violence to hit Syria's capital during nine months of unrest against President Bashar al-Assad. (Courtesy of SANA/Reuters)

Twin car bombs ripped through the morning calm of Damascus on Friday, killing at least 40 people and casting doubt on the ability of a newly arrived team of Arab League monitors to stem Syria’s growing violence.

The explosions shattered two government buildings used by Syrian intelligence and security commanders and ushered in what some analysts feared is a new stage in the nine-month-old uprising. The Syrian government blamed al-Qaeda for the blasts, a claim that drew skepticism from Syrian opposition groups as well as Western governments and intelligence agencies.

But regardless of who carried out the bombings, the attacks marked a grim zenith in what was already the bloodiest week of the uprising. They were also a slap to international monitors from the Arab League, who began arriving this week to put pressure on Syrian authorities to halt attacks on opposition forces.

The bombings came as government troops were battling pockets of armed defectors in several parts of the country, despite an agreement with the Arab League to withdraw soldiers from populated areas. President Bashar al-Assad, who faces growing domestic opposition as well as tightening international sanctions, has been under international pressure to accept monitors and to allow independent media into the country.

The apparent targeting of Syria’s intelligence apparatus seemed to mark a significant escalation in unrest that has thus far seen the army deployed to quash protests in centers of opposition such as the city of Homs and that has included some clashes pitting the army against defectors and armed rebels.

Independent analysts said the attack could fuel panic and paranoia among an increasingly frightened population, particularly in Damascus, which has been largely spared until now.

“It signals that this conflict is getting much worse, not better and not simmering down,” said Andrew Tabler of the Washington Institute for Near East Policy.

The explosions in the Kfar Sousa area of the capital came after nine months of anti-government demonstrations that have grown increasingly violent, with soldiers defecting and rebels taking up arms in response to a heavy security crackdown.

Assad has blamed the uprising on extremists, foreigners and armed gangs. After the bombings Friday, the Associated Press reported, the government quickly escorted the Arab League team to the gory scene and said the attacks backed its claims that the turmoil is not a popular uprising.

“We said it from the beginning: This is terrorism. They are killing the army and civilians,” Deputy Foreign Minister Faisal al-Miqdad told reporters outside the headquarters of the General Security Directorate.

In Washington, U.S. officials condemned the attacks while acknowledging uncertainty about who was behind them. Intelligence officials questioned the veracity of the government’s assertions — issued by Syrian-run news media — that al-Qaeda was responsible, noting that it would be difficult for al-Qaeda to carry out such an ambitious operation in the tightly controlled police state. However, some analysts noted that the attacks bore many of al-Qaeda’s hallmarks, including the coordinated use of suicide bombers against heavily guarded targets.

“For the moment, it’s unclear who did the bombings,” said a U.S. official privy to intelligence files from the region.

Syrian opposition groups denied any involvement in the bombings. Some opposition figures theorized that pro-Assad forces could have staged the attacks to discredit the opposition and buttress state claims that “terrorists” are behind the uprising.

The blasts came a day after a technical committee from the Arab League arrived in Damascus to discuss implementing an agreement for monitors to come into the country and the military to withdraw from centers of protest.

The official Syrian Arab News Agency reported that 44 people were killed and 166 wounded in attacks that “were carried out by two suicide bombers with two booby-trapped cars.” The agency published gruesome photos of the carnage on its Web site.

Mutilated and torn bodies lay amid rubble and burned cars outside the General Security Directorate and a building housing a branch of the military intelligence service, as bystanders and ambulance workers carried victims to vehicles, the Associated Press reported.

State Department spokesman Mark Toner expressed sympathy for the victims of the bombing, saying, “There is no justification for terrorism of any kind.” But he stressed that the violence should not derail the Arab League’s efforts to monitor human-rights abuses.

“We hope that this mission will proceed unfettered in an atmosphere of nonviolence,” Toner said. “The burden is on the regime to cooperate fully and quickly with the monitoring mission.”

Citing a slow shift in recent months from peaceful protests to violent opposition, some analysts said it was possible — though not certain — that the bombings were the work of an opposition group.

“We are not going to know unless someone makes a claim,” said Anthony Cordesman of the Center for Strategic and International Studies in Washington. It could be useful for the Syrian government to blame al-Qaeda for such an attack, he added, even if there is no claim by the group or evidence that it was responsible.

“Just as Gaddafi found it convenient early on to blame everything on al-Qaeda,” Cordesman said, “so Assad finds it a very convenient way to say, ‘This is not a domestic resistance.’ ” He referred to Moammar Gaddafi, the Libyan strongman who was driven from power in August and killed by rebels who captured him in October.

Salman Shaikh, director of the Brookings Doha Center in Qatar, a branch of the Washington-based Brookings Institution, said he was “deeply skeptical” of claims that either al-Qaeda or an opposition group could have staged such an attack in Damascus.

“Syria doesn’t really have a record of this,” Shaikh said. “The security forces have not lost control of the situation to such an extent that this would seem likely.”

Shaikh also said it seemed suspicious that the media reported the attack so quickly, with pictures showing the car bombs already cleared away.

The Syrian Revolution General Commission called the bombings a “pathetic move” by the Syrian government and a “feeble attempt to plant fear and terror in the hearts of civilians.”

Warrick contributed from Washington.