Syrian opposition forces have recaptured key towns in the northern Aleppo countryside after intense battles with regime forces, activists have told Al Jazeera.

Opposition said regime forces had been supported by Hezbollah and Iranian fighters.

Meanwhile, the UK-based Syrian Observatory for Human Rights (SOHR), said regime forces had withdrawn to the town of Bashakuy further south in Aleppo province.

At least 248 combatants, including 129 regime soldiers and 119 opposition fighters have been killed since the fighting started on Tuesday, according to SOHR.

The fighting started when regime forces launched a sudden offensive and captured three opposition held towns of Rityan-Hardatnin-Bashkuy that hold a strategic position and cut opposition final route to the city.

'Freeze hostilities'

Earlier on Saturday, SOHR said regime forces had also bombarded places in the town of Hayyan, leaving several people wounded, some of them in critical condition.

Meanwhile, UN Secretary General Ban Ki-moon has called for an immediate de-escalation of the conflict in Syria to give civilians some relief and allow a step towards a political solution to the four-year war, a spokesman for the UN chief said on Friday.

The UN chief also urges the Syrian regime to honor its commitment of a six-week suspension of airstrikes and artillery shelling in Aleppo, as proposed by the UN special envoy to Syria Staffan de Mistura, said Dujarric.

The overall war in Syria has killed at least 220,000 people and sent more than 3.8 million people fleeing the country.

PHOTO CAPTION

Opposition fighters take positions after what they said was an offensive against them by forces loyal to Syria's President Bashar al-Assad that attempted to advance in the village but failed to, in Ratian, north of Aleppo February 18, 2015.

Al-Jazeera