Turkey-backed Syrian rebel forces besieging Islamic State-controlled al-Bab have gained full control of the highway linking the town to Aleppo with intense ground and air fire support, the Turkish military said on Wednesday.

In its daily round-up of the near four-month-old "Euphrates Shield" operation to push Islamic State away from the border area, the army said Turkish warplanes had destroyed 48 IS targets and killed 15 militants.

Four Turkish soldiers were slightly wounded when the vehicle they were traveling in was damaged by a roadside blast, it added.