DAMASCUS - Suicide attackers detonated massive bombs in Damascus during the morning rush hour on Thursday, killing at least 55 people and wounding nearly 400 in the deadliest bombings of Syria's 14-month uprising.
UN-Arab League envoy Kofi Annan strongly condemned the attacks, which President Bashar al-Assad's government blamed on "terrorists" and the opposition accused his regime of carrying out to threaten UN observers.
State television aired gruesome footage of the aftermath of the twin explosions in the neighbourhood of Qazzaz, which the UN mission chief later visited and appealed for help to end the bloodshed.
"Two explosions caused by terrorists took place on the freeway in the south of Damascus," the television said, adding the blasts occurred "as people were heading to work and children to school."
Syria's interior ministry, cited on TV, said the suicide attackers used a tonne of explosives in the bombings, killing at least 55 people and wounding 372.
It added that emergency workers filled 15 bags with body parts of others who died, and that the blasts also destroyed around 200 cars.
The Syrian Observatory for Human Rights, a Britain-based monitoring group, said the bombings targeted an intelligence base and killed 59 people, including civilians and security personnel.
The opposition Syrian National Council accused Assad's regime of staging the bombings.
"The regime is behind this," the exile group's Samir Nashar said, adding the aim was to warn UN observers they were in danger and to impress upon the international community that the regime was battling "terrorists."
"This is the only way for the regime to claim that what is happening in Syria is the work of terrorist gangs and that Al-Qaeda is expanding its presence in Syria," he said.
The blasts struck near a nine-storey security building, the facade of which was destroyed along with several surrounding residential complexes, an AFP correspondent reported.
Television showed images of a woman's charred hand on a steering wheel, her gold bracelets dangling from her wrist.
Other burnt and mangled bodies lay in the street amid the carcasses of smouldering vehicles.
"Is that the freedom you want? Students from schools and employees going to work are dead," shouted one man in the middle of the destruction.
Major General Robert Mood, chief of a UN observer mission who visited the site of the explosions, appealed for help to stop the bloodshed.
"This is yet another example of the suffering brought upon the people of Syria. We, the world community, are here with the Syrian people and I call on everyone within and outside Syria to help stop this violence," he said.
The attacks came a day after the Norwegian general escaped unharmed when a roadside bomb exploded as he led a team of UN observers into the flashpoint southern city of Daraa. Ten Syrian troops escorting them were hurt.
In Geneva, Annan's spokesman Ahmad Fawzi said in a statement that he "condemns in the strongest possible terms the attacks that took place earlier today in Damascus."
"Any action that serves to escalate tensions and raise the level of violence can only be counter-productive to the interests of all parties.
"The Joint Special Envoy calls on all parties to avoid further bloodshed and to protect civilians. The Syrian people have already suffered too much," it concluded.
The European Union also condemned the attacks which it described as "an act of pure terrorism."
Damascus has been the target of a number of bombs in the past few months. Suicide bombers hit two security service bases in the capital on December 23, killing 44 people, in attacks the regime blamed on Al-Qaeda but which the opposition said were the work of the regime itself.
Commenting after Wednesday's Daraa attack, UN leader Ban Ki-moon warned Syria's government and opposition there is only a "brief window" to avoid civil war and indicated the future of the ceasefire monitoring mission was in doubt.
Highlighting an "alarming upsurge" of roadside bombs, alongside government attacks, Ban said in New York that both sides "must realise that we have a brief window to stop the violence, a brief opportunity to create an opening for political engagement between the government and those seeking change."
He also warned that such bombings cast doubt on the future of the mission set up to monitor a month-old truce brokered by UN-Arab League envoy Kofi Annan.
If the violence did not stop, Ban said he feared "a full-scale civil war with catastrophic effects within Syria and across the region."
Elsewhere in the country on Thursday, regime forces killed at least three civilians, including a child, the Syrian Observatory said.
The watchdog says that almost 12,000 people, mostly civilians, have been killed in Syria since the revolt, inspired by Arab Spring uprisings, broke out in March last year.
About 800 of them have died since the UN-backed truce was supposed to have taken effect on April 12.