UNITED NATIONS (Reuters) -- The UN Security Council strongly condemned the "terrorist attacks" in Syria on Thursday, urging all parties to the 14-month conflict to cease armed violence and comply with a UN-backed peace plan.

Two suicide car bombers killed 55 people and wounded 372 in Damascus earlier on Thursday, state media said, in the deadliest attacks in the Syrian capital since an uprising against President Bashar Assad began last year.

"The members of the Security Council condemned in the strongest terms the terrorist attacks that occurred in Damascus, Syria, on 10 May, causing numerous deaths and injuries," the 15-member body said in a statement.

The Security Council also called on all parties in Syria to "immediately and comprehensively" implement UN-Arab League envoy Kofi Annan's six-point peace plan, in particular to cease all forms of armed violence.

The 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."

The statement was released after a Security Council debate on the global fight against terrorism during which Syrian UN Ambassador Bashar Ja'afari said there had been an increase in "the scale and frequency of terrorist activities and operations in Syria" since a shaky April 12 truce took hold.

He also said that at the same time as the Damascus bombings Thursday, there had been an explosion in the Syrian city of Aleppo "which led also to several civilian victims and massive damages to private property." He gave no further details.

Syria has barred most independent journalists from the country, making it is difficult to verify reports of attacks and casualties.

Ja'afari accused "some Arab, regional and international states" -- without naming any -- of sending fighters, funds and arms to "terrorist groups" in Syria.

He called on the council "to take immediate necessary action in order to stop all terrorist activities taking place in Syria and to exert maximum pressure on the states which are facilitating and financing and inciting the groups that are perpetrating this terrorism."

UN Secretary-General Ban Ki-moon earlier on Thursday strongly condemned the suicide car bombings in Syria and called on all sides to distance themselves from "indiscriminate bombings and other terrorist attacks."