Opposition and regime forces have clashed in the country's Idlib province, as fighting intensified in northern areas of the country.
Regime jets on Sunday pounded the town of Binesh in Idlib, while opposition forces shelled a regime checkpoint in Saida, said the Syrian Observatory for Human Rights.
Also on Sunday, a father and his three children were killed in Raqa province when regime planes bombed their home, the observatory said.
The attacks follow days of fighting in Latakia province, which borders Idlib.
The coastal Latakia province is the stronghold of President Bashar al-Assad's Alawite minority and has remained relatively immune to violence. However, opposition groups have captured about 10 Alawite villages in the mountainous Jabal al-Akrad area of the province.
Al Jazeera's Zeina Khodr, reporting from Antakya in neighbouring Turkey, said the opposition forces now controlled areas in Latakia's countryside. However, they have not yet been able to advance to the coast.
The regime has hit back, sparking fierce fighting that has left dozens dead on both sides, according to the observatory.
On Saturday, at least 20 people were killed in several regime air strikes on the Sunni opposition-held town of Salma in the Jabal al-Akrad area, it said.
At least six of those killed were Syrian opposition fighters, while four were foreigners, said Rami Abdel Rahman, who heads the observatory.
She said that while the regime maintained the upper hand, losing Latakia would be a symbolic blow.
PHOTO CAPTION
Damaged military vehicles, including a tank, which belonged to the Syrian Army are seen at the Minnig military airport, after it was seized by opposition forces, August 11, 2013.
Al-Jazeera