At least 70 fighters have been killed in less than 24 hours of fierce clashes between pro-regime forces, jihadists and rebels in Syria's Aleppo province, a monitor said Wednesday.

Pro-regime fighters -- backed by regime and Russian air strikes -- retook the villages of Zaytan and Khalasa to the southwest of Aleppo city after losing control of them hours earlier, the Syrian Observatory for Human Rights said.

But Al-Nusra Front, Syria's Al-Qaeda affiliate, launched a counterattack to retake Khalasa on Wednesday morning, Observatory chief Rami Abdel Rahman said.

‘Khalasa is on a high hill overlooking large parts of the south of Aleppo province,’ he said.

The area overlooks the regime's supply road around the south of Aleppo city, linking the government-held Nayrab airport to the city's southeast and areas controlled by regime troops to its west, he said.

Rebel- and jihadist-held areas in the south of Aleppo province faced heavy strikes and shelling overnight, said the Britain-based monitor, which relies on a network of sources inside Syria to gather its information.

The regime also pounded a key supply route and areas north of Aleppo city overnight, the Observatory said.

The Al-Watan newspaper, which is close to the regime, reported Russian air strikes on the province on Wednesday.

‘Russian fighter jets resumed their missions in Aleppo with force, targeting positions of Al-Nusra Front and allied militias,’ it said.

Moscow launched air strikes in support of the Damascus regime in September.

Aleppo was once Syria's commercial powerhouse, but it has been a battleground since 2012 when rebels seized the east of the city confining the army to the west.

In western Aleppo, rebel shelling killed two people and injured another three on Wednesday, official news agency SANA reported.

Syria's war has killed more than 280,000 people and displaced millions since it started with the brutal repression of anti-government protests in 2011.