Arab League monitors are to meet Syria's top diplomat on Saturday, a day after suicide bombers killed 44 people in attacks Damascus blamed on Al-Qaeda but the opposition said were the regime's work.
The bombings, the first against the powerful security services in the heart of the capital since an uprising against President Bashar al-Assad began in March, came a day after the arrival of an advance group of monitors.
"Forty-four people, civilians and security forces, were killed and 166 others injured in the two terrorist operations," the interior ministry said of the attack which state media and government officials blamed on Al-Qaeda.
"On the first day after the arrival of the Arab observers, this is the gift we get from the terrorists and Al-Qaeda, but we are going to do all we can to facilitate the Arab League mission," said Deputy Foreign Minister Faisal Meqdad.
The delegates are in the country to pave the way for the arrival of a team of Arab League observers tasked with overseeing an end to the bloodshed, and will hold talks with Foreign Minister Walid Muallem.
Muallem has said he expects the observers to vindicate his government's contention the unrest is the work of "armed terrorists," not overwhelmingly peaceful protesters as maintained by Western powers and human rights watchdogs.
Asked by reporters to comment on suggestions the bombings had been engineered by the regime itself, Meqdad shot back: "Anyone who makes such allegations is a criminal."
But the opposition Syrian National Council said in a statement that: "The Syrian regime, alone, bears all the direct responsibility for the two terrorist explosions."
The regime wanted to create the impression "that it faces danger coming from abroad and not a popular revolution demanding freedom and dignity," it added.
The UN Security Council condemned the attacks but remained deadlocked on a full resolution on the crisis with the Russian and US ambassadors trading personal barbs.
While not rejecting Syria's account of the events, France accused the regime of trying "to mask the reality of the repression, notably by transferring political prisoners to secret jails".
Ban Ki-moon's spokesman said the UN leader was "gravely concerned" about the escalation and urged the government to "fully and speedily" implement the Arab League plan.
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Syria's deputy foreign minister was accompanied to one of the bombing sites by Arab League Assistant Secretary General Samir Seif al-Yazal, head of the advance team which arrived Thursday.
"What has happened is regrettable but the important thing is that everyone stay calm," Yazal told reporters.
"We are going to press on with our work. We have started today, and tomorrow (Saturday) we will meet Walid Muallem."
Yazal's nine-member team is making logistical arrangements for the arrival of the first observers, who will eventually number between 150 and 200.
In Cairo, the Arab League's Ahmed Ben Helli said the mission will head to Syria on Monday, grouping more than 50 experts in politics, human rights, military issues and crisis management, the official MENA news agency reported.
The mission is part of an Arab plan endorsed by Syria on November 2 that also calls for the withdrawal of the military from towns and residential districts, a halt to violence against civilians and the release of detainees.
Syria says more than 2,000 security force personnel have been killed in attacks by armed rebels since March.
But opposition leaders have charged that Syria's agreement to the mission after weeks of prevarication was a mere "ploy" to head off a threat by the Arab League to go to the UN Security Council over the nine-month crackdown which the world body says has killed more than 5,000 people.
There was no let-up in the bloodshed on Friday with human rights activists reporting at least 21 civilians killed across the country, the majority of them by security force fire.
The bodies of four civilians who had been arrested were found Saturday with signs of torture in restive Homs province, activists said, urging the visiting Arab League team to document the cases.
"The corpses of four citizens were found this morning in the streets of the town of Hula and a fifth citizen was found in a critical condition," the Syrian Observatory for Human Rights said in a statement received in Nicosia.
The central province of Homs has been a focal point of the government's crackdown on anti-regime demonstrations as well as the site of fierce clashes between the army and mutinous soldiers, the activists say.
"Security forces and 'Shabiha' (pro-regime militia) groups had arrested them after midnight on Friday-Saturday in the Al-Bustan neighbourhood... There were signs of torture on the bodies of the martyrs," the Observatory said.
The watchdog demanded that the Arab League "immediately head to the town of Hula to document this flagrant violation of human rights which is just the tip of the iceberg of what is going on in Syria."