A ground-to-ground missile was fired on a town in northern Syria on Sunday and killed at least four civilians, two of them children, a watchdog reported, as violence shook several Damascus neighbourhoods.

Anti-regime activists of the Aleppo Media Centre said the missile, which slammed into a residential area of Tal Rifaat, was a Scud, although this could not be independently verified.

The attack also killed two women, wounded several other people and destroyed many homes in the town in Aleppo province, the Britain-based Syrian Observatory for Human Rights said.

The Syrian Revolution General Commission, an activist network, reported 30 wounded and 10 houses destroyed, adding a mother and her two daughters were among the dead.

"The toll could rise, with bodies buried under the rubble," said the Observatory.

Amateur video footage posted online by activists showed men clearing away debris in the dark and then removing the body of a child, as cries are heard from the crowd.

In February, the Observatory cited activists as saying the army fired Scuds on Aleppo city, killing 58 people, including 36 children.

Damascus has denied using Scuds.

Elsewhere in Aleppo province, fierce clashes raged inside the Kwiyres military airport, as rebels tried to seize the facility.

Since the beginning of the year, rebel forces have been fighting what they call the "battle of the airports in Aleppo" to deprive the regime of a key supply route.

Rebels have set their sights on the Aleppo international airport, along with the Jarrah, Kwiyres, Minnigh and Nayrab military fields. They took the Jarrah military airport on February 12.

Meanwhile, in Idlib province, the Observatory reported clashes around the Abu al-Dohur military airport, which rebels have laid siege to for about a month.

"The rebels have broken into the airport but they are still on the periphery and are engaged in violent clashes with soldiers," Observatory director Rami Abdel Rahman told AFP.

The Observatory also reported clashes in several districts of the capital Damascus, including in the northern area of Barzeh where fighting has been raging for several days between rebels and regime forces.

Regime aircraft raided the industrial zone in Qabun district of northern Damascus and Jubar in the east while shells rained in the afternoon on the Yarmuk Palestinian refugee camp in the south of the capital, the watchdog said.

Fighting also rocked Daraya, south of Damascus, which according to the town's rebel opposition council the army has been trying to overrun for the past 167 days.

Insurgents reported air raids and artillery fire on Daraya, saying there was a shortage of medicines due to the "siege" imposed by regime forces.

Meanwhile, the Observatory reported that a "man from the (jihadist) Al-Nusra Front (rebel group) blew up a car near a gathering of regime forces in the town of Kamam" in Homs province.

Sunday's violence killed at least 42 people across Syria, reported the watchdog which relies on a vast network of activists and medical staff inside Syria.