The UN Security Council on Friday strongly condemned the terrorist attacks in the Syrian capital of Damascus.

"The members of the Security Council condemned in the strongest terms the terrorist attacks that occurred in Damascus, Syria on 23 December, causing scores of deaths and injuries," said a statement issued by Vitaly Churkin, Russia's permanent representative to the United Nations who holds the rotating council presidency for December.

"They expressed their deep sympathy and sincere condolences to the victims of these heinous acts and to their families, and to the people of Syria," the statement said.

"The members of the Security Council reiterated their determination to combat all forms of terrorism, in accordance with its responsibilities under the Charter of the United Nations," the statement said.

Earlier on Friday, UN Secretary-General Ban Ki-moon said that he was "gravely concerned at the escalating violence in Syria," and stressed that "all violence is unacceptable and must stop immediately," according to a statement issued here by Ban's spokesman.

On Friday, crowds of Syrians flocked to main squares nationwide to condemn the two terrorist attacks that struck two security branches earlier in the day which killed more than 40 people and wounded more than 160 others.

"The members of the Security Council reaffirmed that terrorism in all its forms and manifestations constitutes one of the most serious threats to international peace and security, and that any acts of terrorism are criminal and unjustifiable, regardless of their motivation, wherever, whenever and by whomsoever committed," the council statement said.

"The members of the Security Council reminded states that they must ensure that measures taken to combat terrorism comply with all their obligations under international law, in particular international human rights, refugee and humanitarian law," the statement said.

Syria's Interior Ministry said Friday that most of the victims were civilians.

"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."

Two suicide bombs rocked two security centers in central Damascus earlier on Friday, 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.