A damaged car is seen where a car bomb blew up at security sites in Damascus December 23, 2011, in this handout photograph released by Syria's national news agency SANA. [Photo/Agencies]

DAMASCUS - The death toll of the twin attacks on intelligence centers in the Syrian capital of Damascus on Friday has risen to 44, while 166 others were injured, most of them civilians, Syria's interior ministry said Friday.

"The attacks reflect a new escalation of terrorist acts in Syria," the ministry said in a statement, adding "the style of the attacks refers to al-Qaida."

The ministry appealed to the Syrian people to report any suspicious act "to cut the hand of terrorism."

Earlier on Friday, two suicide bombs rocked two security centers in central Damascus, the worst violence since protests against President Bashar al-Assad erupted in mid-March. The bombing came only a day after the Arab League (AL) observers arrived in the capital to monitor the situation on the ground.

The blasts struck the headquarters of the security department building and the Region Security Branch, leaving rubble and twisted debris covering the road that is lined with burned cars.

Syria's state TV said security forces have arrested a suspect, adding that terrorists carried out the two blasts at sites with heavy traffic and near an orphanage.

Imams and preachers condemned the attacks and stressed in a statement carried by state-run SANA news agency that Islam has nothing to do with any terrorist attack that targets the security of the homeland, citizens, unity and stability of the country.

UN Secretary-General Ban Ki-moon on Friday said he is "gravely concerned with the escalating violence in Syria," and stressed that "all violence is unacceptable and must stop immediately."

In the statement, the secretary-general urged "a credible, inclusive and legitimate Syria-led process of comprehensive political change that will address the democratic aspirations of the Syrian people."

Besides, Lebanese Foreign Minister Adnan Mansour also strongly condemned the acts, saying the heinous crime is the newest in a series of crimes against the Syrian people and the national army, which are aimed at undermining Syria and threatening the unity of the Syrian people.

"We offer our heartfelt condolences to the families of the martyears and express our deep grief and condemnation of this heinous crime ... We also wish the injured a speedy recovery and hope that security and stability would be restored to Syria," he said.