Turkish troops and Syrian opposition fighters enter IS-held Al-Bab town

Turkish forces and allied insurgents have for weeks pressed an operation codenamed Euphrates Shield to drive the jihadists from the flashpoint town.

The Syrian Observatory for Human Rights said Turkish forces and allied militias entered Al-Bab from the west and then took full control of its western suburbs after fierce clashes with the jihadists.

The fighting coincided with “Turkish shelling and intensive air strikes” on Al-Bab, the Britain-based monitor said.

It said at least six civilians were killed by Turkish artillery fire and air strikes.

Al-Bab is the jihadist group’s last stronghold in the northern province of Aleppo and is also being targeted by regime forces.

While Turkish-led forces have been advancing from the north, east and west, Syrian government troops are attacking from the south.

On Monday, Syrian troops severed a road leading into the town from the south and by Friday they were just 1.5 kilometres (less then a mile) from the southern outskirts of Al-Bab.

Turkey began an unprecedented campaign inside Syria in August, targeting both IS and Kurdish militia.

After initial rapid progress, the campaign has been mired since December in the deadly fight for Al-Bab. Turkey’s Dogan news agency says 66 Turkish soldiers have been killed in the campaign since it started, mostly in IS attacks.

And on Thursday, three Turkish soldiers were killed when a Russian air strike accidentally hit their position in an attack targeting IS in Al-Bab.

Moscow said it was an accident and is being investigated.

Despite backing opposite sides in Syria’s conflict — Moscow is a government ally while Turkey supports the opposition — the two countries have worked closely in recent months.

They helped broker a nationwide ceasefire in place since December 30, and sponsored a round of peace talks last month in the Kazakh capital, Astana.

Al-Bab has been under IS control since 2014, when the group seized large swathes of territory in Syria and neighbouring Iraq, proclaiming its self-described caliphate.