Syrian troops shelled areas of Homs city and the Houla region where they clashed with rebels on Saturday, as a monitoring group said rebels seized a village near the Turkish border.
Rebels captured Khirbat al-Joz in the northwest province of Idlib near the border after a fierce battle in which 25 troops and three insurgents were killed, the Syrian Observatory for Human Rights said.
Nearly 80 percent of towns and villages along the Turkish border are outside the control of Damascus, according to the group.
AFP correspondent have passed through large swathes of territory in the Idlib and Aleppo provinces of northern Syria that have fallen outside government control, with residents managing their own affairs.
Four civilians, including a woman, and six rebels were killed in the Houla region of the central province of Homs in clashes and shelling by regime forces, the Britain-based Observatory said.
In March, at least 108 people, including 49 children and 34 women, were killed in the town of Houla during a two-day army offensive that began with heavy shelling.
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In Homs city, the Observatory reported fierce shelling as clashes raged between the army and rebels on the outskirts of Baba Amr neighbourhood and other areas under army siege.
The Local Coordination Committees, a network of activists on the ground, said that fierce clashes broke out in the rebel districts of Khaldiyeh, Jurat al-Shiyah and Qasur.
"The Free Syrian Army (FSA) continues to defend against the attempts by regime forces to storm the neighbourhoods. Artillery and rocket shelling of the city continues," the LCC said.
In Syria's second city Aleppo, residents reported fierce fighting in the east, while an AFP reporter on the ground said most streets were cut off to cars by army or rebel checkpoints.
Fighting was also reported on the outskirts of the Tareq al-Baba district of Aleppo.
"I've never seen so many rebels in the area. They've put mortars on the rooftops and municipal buses at the entrances to Tareq al-Bab to keep out the army," said a 40-year-old medical laboratory worker living in the district.
Nationwide, at least 75 people were killed on Saturday -- including 38 soldiers, 25 rebels and 12 civilians -- according to a revised count from the Observatory, which gave a death toll of 133 for Friday.
Since the uprising against President Bashar al-Assad's regime erupted in March last year, a total of more than 31,000 people have been killed, according to the group.