Syrian warplanes attacked Islamist militants near the northern city of Aleppo on Sunday, both sides said, as the government tried to push back an insurgent advance in the area.

Dozens of air strikes hit near the town of Khan Touman, which rebels took from forces loyal to the government and its ally Iran late on Thursday, insurgents and state media reported.

Aleppo is one of the biggest strategic prizes in a war now in its sixth year. Through much of the conflict, it has been divided into government and rebel-held zones. Aleppo's surrounding area is also strategically important because it encompasses valuable supply routes into neighboring Turkey.

The Syrian army reported on Sunday that it had hit hard what it described as terrorist groups, but did not give further details about territorial gains.

A mouthpiece for the Iran-backed, Lebanese militia Hezbollah, which is supporting Syrian government forces in the area, reported "heavy fighting" against "hardline Sunni Muslim rebels." Since Syria's main ally, Russia, entered the war in September, regime forces made significant advances in the northern regions surrounding Aleppo.

Footage uploaded by rebels from the Khan Touman area show them targeting regime forces with what appeared to be American TOW guided anti-tank missiles.

The Nusra Front posted on social media that it was advancing further south, towards the town of al-Hader — a stronghold for the Hezbollah forces supporting the Syrian government.

Some fighting continued in Aleppo, despite the shaky US and Russian brokered ceasefire there. It began last Wednesday and was meant to last 48-hours, but according to the Syrian state news agency, it is being extended until Monday.

Rebel groups inside Aleppo reported that the Syrian army shelled and bombed their posts overnight near a frontline in the western part of the city.

"We don't know how to take cover from the intensity of rockets and airstrikes that are showering us," Ahmad al Wawi, a fighter from a rebel coalition group told Reuters.

The UK-based Syrian Observatory for Human Rights (SOHR) said that rebels fired rockets at residential areas in government-controlled zones. At least seven people were injured — partly due to a building which collapsed after being struck by a missile.

Rebels are seeking to take over the area that would allow them to enter the heart of government-held parts of Aleppo.

The Observatory also reported that an airstrike targeted the rebel-held town of Kafrnaha, in the western Aleppo countryside, killing several people at a hospital.

The attack on the hospital comes after a string of recent attacks on medical facilities in Aleppo including the al Quds hospital where 50 people were killed. Video showed what remained of the alleged hospital, including damaged ambulances.

Separately, the Amaq news agency, which is associated with Islamic State, said the group had destroyed a gas plant in the desert outside the central city of Palmyra on Sunday. IS were driven out of the ancient city two months ago, but continue to be active in the surrounding area.

Overnight, Turkey said its special forces also carried out a counter-terrorism operation in Syria, not far from the southeastern Turkish border city Kilis. According to Yeni Safak, a Turkish news outlet, special forces prepared for ten days ahead of the operation, and were acting on information gleaned by their intelligence teams. They raided rocket positions operated by Islamic State militants who, in recent month, have been driving up to the border, firing rockets and then driving away. The rockets are not guided, but they frequently hit Killis, where several people have been killed in cross-border rocket attacks.