At least 13 people, including five children, have been killed after Syrian government aircraft pounded a rebel-held city in the country's north east, activists said.
The Britain-based Syrian Observatory for Human Rights said the air raids - eight strikes in total - hit the north-eastern city of Raqqa.
Four women were among the dead and dozens of people were wounded, the observatory said.
Rebels captured Raqqa, the capital of the province of the same name, in March. It is the only major urban centre to fall entirely under opposition control since the Syrian conflict began in March 2011.
Rebels also control territory in the north and parts of Aleppo, Syria's largest city and its commercial centre.
President Bashar Assad's forces have relied heavily on air power in the last year to regain control of opposition-held territory, particularly in the north and along the border with Turkey.
Last week, at least 50 people were reported killed in two helicopter attacks on a rebel-held town near Aleppo.
Activists say airstrikes often precede government ground offensives. Assad's troops may be mounting a major operation to recapture territory and bolster its position ahead of peace talks planned for January in Geneva.
Assad's control of Syria's skies is hampering rebels' efforts to hold on to territory they capture and administer it with any efficiency.
Infighting between rebel groups is another major factor that has weakened opposition forces in their fight to topple Assad's government.
The observatory said fighters from the Islamic Front ousted the FSA from the Bab al-Hawa crossing point on Saturday, taking control over the administrative buildings and weapons storage sites.
The observatory did not report any violence during the takeover. There was no immediate confirmation of the development from the FSA commanders.
The Islamic Front formed last month, uniting rebel groups who say they want to transform Syria into an Islamic state after Assad's overthrow.
Its formation is in part meant to stave off challenges from the more radical al Qaida-linked Islamic State in Iraq and the Levant, which has emerged over the last year as one of the most effective fighting forces on the opposition side.
The Syrian conflict started as largely peaceful protests against Assad's rule. Over the past year, it turned into a fully fledged civil war in which at least 120,000 people have been killed, activists say.
In western Syria, government troops backed by Hezbollah fighters were battling al Qaida-linked rebels for control of a town located along the country's main north-south highway, according to the observatory and state media.
The road holds strategic value for both sides, and serves as a crucial link between the capital Damascus and northern Syria as well as government strongholds along the Mediterranean coast.
The Organisation for the Prohibition of Chemical Weapons said this week it would consider using the highway to transport Syria's chemical weapons to the port of Latakia before they are taken out of the country for destruction.
Saturday's clashes are concentrated around the town of Nabek. The section of the highway near the town has been closed for 18 days because of the heavy fighting, according to the observatory which obtains its information from a network of activists on the ground.
The Syrian state news agency SANA said the army killed "scores of terrorists" in Nabek, using the state media's term for rebels. Foreign fighters and Islamic extremists were among those who died in the Nabek fighting, SANA said.
Assad's troops also destroyed rebel hideouts and their weapons, positioned just south west of the town, SANA said. It cited an anti-aircraft missile launcher and two explosives-laden cars among the weapons that were destroyed by the troops on Saturday.