BEIRUT- The Syrian army said on Monday it had taken full control of dozens of towns in Aleppo's northwestern countryside and it would press on with its campaign to wipe out militant groups "wherever they are found".

The advances were made after President Bashar al-Assad's forces drove insurgents from the M5 highway linking Aleppo to Damascus, reopening the fastest route between Syria's two biggest cities for the first time in years in a big strategic gain for Assad.

Backed by heavy Russian air strikes, the government forces have been fighting since the start of the year to recapture the Aleppo countryside and parts of neighbouring Idlib province where anti-Assad insurgents hold their last strongholds.

Government air strikes on Monday hit Darat Izza, near the Turkish border about 30 km (20 miles) north of Aleppo city, wounding several civilians and forcing two hospitals to close, according to hospital staff.

Wtnesses also reported air strikes in southern areas of Idlib province.

The advances have sent hundreds of thousands of Syrian civilians fleeing towards the border with Turkey in the biggest single displacement of the nine-year-old war.

It has also upset the fragile cooperation between Ankara and Moscow, which back opposing factions in the conflict.

Turkey and Russia began a new round of talks in Moscow on Monday after several demands by Ankara that Assad's forces should back down and a ceasefire be put in place.

Russian Foreign Minister Sergei Lavrov said that militant attacks on Russian bases and Syrian positions have continued and "it is not possible to leave this unanswered".

"Troops from Russia and Turkey on the ground in Syria, in Idlib, are in constant contact with each other, looking at changes in the conditions. They have a full understanding of each other," said Lavrov.

However, the Syrian armed forces said in a statement they would push on with what they called their "sacred and noble task to rid what remains of terrorist organisations wherever on Syria's geography they are found".

They had taken full control of dozens of towns in Aleppo's northwestern countryside, they said.

Pro-Damascus Al-Watan newspaper said the M5 highway, a vital artery in northern Syria, would be ready for civilian use by the end of the week. Aleppo city, once Syria's economic hub, was the scene of some of the most vicious fighting of the war between 2012 and 2016.

The Syrian army had also opened the international roadway from northern Aleppo to the towns of Zahraa and Nubl towards the Turkish border, a military news service run by Lebanon's Assad-allied pro-Damascus Hezbollah group said.

The insurgent forces arrayed against Assad include Western-backed rebels and jihadist militants.

Turkish President Tayyip Erdogan has said his military will drive back Syrian forces if they do not withdraw from Idlib by the end of the month. On Saturday, he appeared to move that date forward, saying Turkey would "handle it" before the end of the month if there was no pull-back.

Alarmed by the new refugee crisis on its border, Turkey has sent thousands of troops and hundreds of convoys of military equipment to reinforce its observation posts in Idlib, established under a 2018 de-escalation agreement with Russia.

(Reporting by Eric Knecht, Tom Perry, Khalil Ashawi; Additional reporting by Alexander Marrow in Moscow; Editing by Angus MacSwan) ((eric.knecht@thomsonreuters.com; Reuters Messaging: eric.knecht.thomsonreuters.com@reuters.net))