Turkey has called on members of the US-led coalition fighting the Islamic State group, to assist in air support to Turkey-backed troops laying siege to the ISIL-held northern Syrian town of al-Bab.

Rebels supported by Turkish troops are battling ISIL in the "Euphrates Shield" operation, launched almost four months ago.

The operation aims to sweep the Sunni hardliners and Kurdish fighters from Turkey's border with Syria.

Turkish officials confirmed that a total of 226 ISIL militants had been "neutralised" in latest operations around al-Bab, with intense diplomatic efforts underway to establish a ceasefire across Syria.