Twin explosions rocked security installations in the Syria city of Aleppo, Syrian TV reported on Friday, with reports of at least 25 dead on the scene, with 175 wounded.
The so-called "terrorist explosions" shook Aleppo, Syria's second largest city, only a day after the city's first wave of anti-government demonstrations was reported.
Opposition officials claimed the Syrian regime orchestrated the attack in order to damage the image of anti-Assad forces.
State television showed blood, bodies and shattered concrete strewn across a street outside one of the apparent targets of the blasts, a military security building in the northern city.
Blasts rip through Syrian city of Aleppo
The explosions follow three suicide bombings in the capital Damascus in December and January which killed at least 70 people. Syria's government, blaming al-Qaida for at least some of those attacks, vowed an "iron-fist response".
Aleppo had been spared most of the unrest roiling Syria since anti-Assad protests erupted in March, but it has seen increasing protests and violence in recent weeks.
Syria's private Addounia Television said initial information showed 11 civilians and security force members were killed in an explosion at a military security building and six more at a base for security forces.
A reporter on state television, in a live broadcast from outside the military security complex, said the blast had been audible 20 km away.
The damage shown in the footage suggested the bomb may have detonated on the road outside the five-storey building. A concrete wall around it was badly damaged and its windows were blown out. At least one car appeared blackened and destroyed, and several more were damaged.
Lifting blankets and plastic sheets which had been laid over corpses on the pavement, the reporter showed a body with its head blown off and other bloodied human remains including a limbless torso and a blown off foot.
"We apologize for showing these pictures, but this is the terrorism which is targeting us," the reporter said, at times choking with emotion.
He said children were among the dead, showing a single rollerblade left on the pavement.
"Is this the freedom of Hamad and Erdogan?" one man shouted, referring to Qatari Prime Minister Sheikh Hamad bin Jassim and Turkey's Prime Minister Tayyip Erdogan, who have led the chorus of regional criticism against Assad. "Hamad, you dog," he said.
Syrian television showed similar bloody scenes at the second site, hit by what the reporter said was a car bomb. The blast had gouged a crater several meters (yards) wide, blown a truck onto its side and hurled chunks of concrete over a wide area.
The television showed people pulling body parts out of a black refuse bin for the camera.
The opposition Syrian Observatory for Human Rights earlier quoted Aleppo residents as saying three blasts occurred, including one near a security building. They also reported hearing gunfire.
A resident contacted by Reuters said an area around a military intelligence complex in the New Aleppo district had been sealed off after the explosions.
Also Friday, Syrian activists reported continued intensive military activities in the rebel city of Homs, with residents saying tanks and hundreds of soldiers were surrounding the city's Sunni neighborhoods.
Activists estimate these latest measurers precede another day of battle in the beleaguered city, geared at suppressing opposition forces.
Reports of resumed violence in Homs came after on Thursday opposition sources said military forces loyal to President Bashar Assad has begun stockpiling chemical weapons and equipping its soldiers with gas masks near the rebel town.
Opposition activists said they had received reports that the Syrian army had transferred a significant quantity of grenades and mortars containing chemical agents to a school building in Homs.
The opposition also reported that gas masks were being distributed to soldiers at roadblocks.
Homs has become the focal point of violent confrontations between insurgents and the country's military in recent days, and opposition figures are concerned that the moves could signal the regime's intention to use chemical weapons against its citizens.
News agencies reported over 130 killed in Syria on Thursday, as Assad's government intensified its crackdown on an expanding uprising against his regime.
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