Three people were killed in a car bomb blast in the northern Syrian city of Aleppo Sunday, opposition activists said.
At least 25 others were wounded in the explosion, the Syrian Observatory for Human Rights said.
Syrian state television described the blast as a "terrorist explosion" that occurred between two residential buildings. Opposition activists said the bomb detonated near the city's political security branch.
The blast occurred a day after a series of explosions in Damascus that killed dozens.
A Syrian rebel leader vehemently refuted the government's claim that so-called "terrorists" -- not the regime itself -- were behind the Damascus attacks.
"This is the regime's game. This is how they play their dirty tricks. They carry out these types of explosions from time to time to get more international support and compassion," Capt. Ammar al-Wawi of the rebel Free Syria Army said Sunday. "They are desperately trying to prove to the world that they are fighting against armed gangs, but the reality is they are the ones who are doing all the killings."
At least 20 people were killed in clashes throughout Syria Sunday, including two children and seven soldiers from the Free Syria Army, according to the Local Coordination Committees of Syria. The deaths included nine people killed in Idlib and four people killed in the Damascus suburbs, the network of opposition activists reported.
Four Syrian soldiers were killed in fighting with defectors near the northern city of Jisr al-Shugur, the Syrian Observatory for Human Rights said.
Pro-Assad forces also assaulted and arrested opposition leader Mohamed Sayed Rasas during an anti-government protest in Damascus, the observatory said.
And in Deir Ezzor, heavy gunfire and explosions echoed in the city as government forces and Syrian defected groups clashed, the observatory said.
On Saturday, two explosions rocked parts of Damascus, including Syrian government facilities, state-run media reported.
The Syrian Arab News Agency said 27 people were killed after two "booby-trapped" cars exploded in crowded areas in the capital. The blasts also injured 140 people and caused serious damage to surrounding buildings, SANA said.
One explosion occurred near the customs criminal investigations department, witnesses said, and another struck near the air force intelligence headquarters -- close to where twin bombings struck the offices of two security branches in December. Opposition activists said at the time that the regime staged those attacks to bolster its claim that the government is fighting terrorists, but the government also blamed the same attacks on "terrorists."
In addition to Saturday's attacks in the capital, "two terrorists were killed on Saturday when a booby-trapped car they were driving exploded" in Yarmouk Camp, in the Damascus countryside, SANA said.
Al-Wawi said the Free Syria Army "had nothing to do with these explosions, which caused heavy casualties among civilians, because that's not our mission. We are fighting against the regime brutality, not against our people."
More than a year after the start of the regime's crackdown on dissidents, reports of deaths mount every day.
Opposition activists also described the aftermath of an attack in the Rifai district of Homs province last week, in which most of the surviving 32 children and two women were injured, the activists said.
"The children were tortured -- beaten, abused, fingers cut off, and shot by thugs," said a man who uses the pseudonym Waleed Faris.
Another activist, identified only as Abu Faris, was part of a rescue operation in Rifai. He described seeing abandoned neighborhoods, "tens of bodies" and "horrific corpses, shot, mutilated -- everywhere."
The humanitarian situation across Syria is deteriorating, the International Committee of the Red Cross said in a statement Sunday.
"The ICRC is particularly concerned about vulnerable people, such as those detained in connection with the fighting and those who are sick or injured and need medical care," said ICRC president Jakob Kellenberger, who was scheduled to discuss the situation with Russia's foreign minister in Moscow on Monday.
On Friday, Kofi Annan, the joint U.N-Arab League envoy to Syria, said he was trying to find a peaceful solution to the yearlong violence in Syria and "get unimpeded access" for humanitarian relief.
The former U.N. secretary-general said the situation in Syria is "much more complex" than that in Libya or other nations.
"It's a conflict in a region of the world that has seen many, many traumatic events. I think we need to handle the situation in Syria very, very carefully," he said. "Any miscalculation that leads to major escalation will have impact in the region."
Asked about the prospects of a coalition government, Annan said such a development would have to emerge from talks among Syrians.
Annan met last weekend with the Syrian president in Damascus and the Syrian opposition in Turkey in an effort to end the violence that has swept the nation.
Most reports from inside Syria indicate the regime is slaughtering civilians to wipe out dissidents seeking al-Assad's ouster. The al-Assad family has ruled Syria for more than four decades.
But al-Assad's regime has insisted that "armed terrorist groups" are behind the violence and says it has popular support for its actions.
CNN cannot independently confirm reports of casualties or attacks in Syria because the government has severely restricted the access of international journalists.
But more than 8,000 people have died in the conflict, according to the United Nations. Opposition activists say the overall toll is more than 9,000, most of them civilians.