The United States strongly condemned two blasts that hit Syria's capital on Friday, saying they should not be allowed to impede an Arab League plan aimed at ending a bloody nine-month crackdown against anti-government protests."There is no justification for terrorism of any kind and we condemn these acts wherever they occur," State Department spokesman Mark Toner said in a statement.RELATED:Arab League team in Syria to prepare monitoringSyria launches offensive against rebel hotbed"It is crucial that today's attack not impede the critical work of the Arab League monitoring mission to document and deter human rights abuses with the goal of protecting civilians. We hope that this mission will proceed unfettered in an atmosphere of non-violence," he said.State television reported that two booby-trapped cars blew up at security sites in Damascus on Friday, killing a number of civilians and soldiers, in the worst violence to hit Syria's capital during nine months of unrest against President Bashar Assad.Syria's Dunia television channel put the number of dead from the blasts at 40 with 100 wounded and said most of the casualties were civilians. Dunia cited information from its own correspondents at the scene.Syrian television described the attack as a suicide bombing and said initial inquiries indicated al-Qaida was behind it.Syria's Foreign Ministry spokesman said Friday that Lebanon warned Damascus two days earlier that al-Qaida had infiltrated into Syria from its territory. "The Lebanese authorities warned us two days ago that al-Qaida group infiltrated to Syria from (north Lebanon's town of) Ersal," spokesman Jihad Makdesi told Reuters in an email."And today's suicide bombers caused the death of around 40 and more than 150 injuries, all are civilians and military personnel. Freedom seekers should know that this is not the way to achieve democracy."The attack came a day after the arrival of Arab League officials to prepare for a monitoring team that will check whether Assad is implementing a plan to end the bloodshed.State television broadcast footage of bloodied bodies being carried in blankets and stretchers into ambulances and people hunting through rubble of a badly damaged building.A Reuters cameraman was barred from the site. State television also broadcast shots of bloodied streets littered with mangled human remains and blackened debris.State television said the blasts targeted a state security administration building and a local security branch.The United Nations says Assad's forces have killed more than 5,000 people in their crackdown on the protests, which erupted in March inspired by uprisings in Tunisia, Egypt and Libya. Syria says it faces a campaign by foreign-backed gunmen and terrorist groups. This week it said more than 2,000 members of the army and security forces had been killed since March.Anti-Assad protests have swept the country, although central Damascus and the northern commercial city of Aleppo have remained relatively quiet.A small blast was reported near a Syrian intelligence building in Damascus last month, but there was little damage.But in recent months the mainly peaceful pro-democracy movement has become overshadowed by pockets of armed insurgency that have launched attacks on Syrian security forces.The escalating violence on both sides has raised fears that the country is slipping towards civil war.