Six people were killed and 20 wounded Monday by a car bomb in a Homs district that is home to members of Syrian President Bashar al-Assad's Alawite sect, a monitoring group said.
"At least six people were killed, including women and children, and 20 others wounded in a car bomb attack on the Zahraa district," said the Syrian Observatory for Human Rights, a Britain-based group with a network of contacts inside Syria.
State news agency SANA confirmed the report.
Homs has seen some of Syria's worst violence since the outbreak of the revolt against Assad three years ago, which was met by a brutal crackdown that spawned a civil war.
Only a handful of districts in the heart of the city remain in rebel control. Besieged for nearly two years, residents there survive on little more than herbs and suffer daily shelling.
Fighting raged further north in Syria's second city Aleppo between rebels and regime loyalists, as helicopters dropped a barrel bomb on an opposition area of the city, the Observatory said.
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At least one man was killed by regime shelling, while clashes raged on the city's front lines, the group said, adding that 11 troops were killed in Monday's fighting.
The rebel Army of Mujahideen meanwhile detained prominent female activist Marcel Shehwaro and her friend Mohammad Khalili in Aleppo after she refused to don the Islamic headscarf, according to local activists.
The pair were taken to the Islamic court for questioning, with activists saying they would protest at the court to demand their release.
In Damascus, a mortar hit the central Umayyad square, killing one policeman, a security source told AFP.
North of the capital, the army backed by its Lebanese ally Hezbollah shelled Flita, as it prepared an offensive against remaining rebel enclaves in the Qalamoun mountains near the Lebanon border.
The shelling comes a day after the fall of Yabrud, a key opposition bastion in the Qalamoun area.
More than 146,000 people have been killed in Syria's war, and millions more displaced.