The United States strongly condemned two blasts that hit Syria's capital 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.

"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.

Earlier Friday, two car bomb attacks on Syrian security sites in Damascus killed 44 people and wounded 55 others, most of them civilian, the Lebanese news channel Al Manar said. The Hezbollah-owned TV station cited information from its own correspondents on the ground.

Syria state television reported that two booby-trapped cars blew up at Syrian security sites in Damascus, saying that "terrorist attacks left a number of martyrs, both civilian and military. Most of the victims were civilian," Syrian TV said in a news flash.

Syrian television also claimed that initial investigations indicated that al Qaida was behind the attacks. A witness from the Syrian Observatory for Human Rights said he heard heavy gunfire break out after the blasts.

A witness who spoke to Reuters by telephone said he heard two blasts rock the capital, and a second witness from the Syrian Observatory for Human Rights reported sounds of heavy gunfire after the explosions.

Friday's attacks hit a state security administration building and a local security branch, state television said.

Syrian opposition forces accused the regime of Syrian President Bashar Assad of orchestrating the attacks as a way to throw the country into chaos and blaming the opposition for the ongoing crisis.

The Arab League monitors who began arriving on Thursday will have the job of checking if Syria is complying with an Arab initiative that calls for an end to violence, the withdrawal of troops from the street and the release of prisoners.

On Thursday, a human rights group said that more than 6,200 people including hundreds of children have died in Syria's crackdown on an anti-government revolt.