Rebels and Syrian government forces have clashed in the country's Idlib province, as fighting intensified in northern areas of the country.
Government jets on Sunday pounded the town of Binesh in Idlib, while rebels shelled a government 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 government planes bombed their home, the observatory said.
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The attacks follow days of fighting in Latakia province, which borders Idlib, with concerns growing about the country disintergrating along sectarian lines.
The coastal Latakia province is the stronghold of President Bashar al-Assad's Alawite minority and has remained relatively immune to violence. However, rebel 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 rebels now controlled areas in Latakia's countryside. However, they have not yet been able to advance to the coast.
The government 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 government air strikes on the Sunni rebel-held town of Salma in the Jabal al-Akrad area, it said.
At least six of those killed were Syrian rebels, while four were foreigners, said Rami Abdel Rahman, who heads the observatory.
She said that while the government maintained the upper hand, losing Latakia would be a symbolic blow.
Concerns of divisions
Al Jazeera's Khodr said that there are worries now of the possibility of the country disintergrating, with no political solution in sight.
She said that rebel groups have declared war on the Syrian Kurdish party, the Democratic Union Party (PYD), which has long identified its support for Assad.
"Long standing tensions are now open confrontation after the PYD declared its intention to set up its own temporary administrations."
"There is fear that could lead to an autonomous region in the northeast, the heartland of Kurds, Syria's largest ethnic minority," said Khodr.
"It is not very clear what a post-Assad Syria will look like - but already one divided on geographic lines seems to be emerging," said Khodr.
The regime controls much of southern and central Syria, and the Latakia pocket, while fighters hold northern areas near the Turkish border and along the Euphrates valley towards Iraq.
The northeast corner of the country is now an increasingly in Kurdish control.
Colonel Abdul Jabar al Okaidi, of the FSA's military council, told Al Jazeera: "The idea of division by some Kurds is dangerous. These Kurdish groups are acting on behalf of foreign powers. We will fight to prevent the division of Syria."
Source: Al Jazeera and agencies